Duration of the Preparatory Period in Mine Construction and Ways of Reducing It

S. N. LEONT'EV

(Presented by Professor, Doctor I. A. Balashev)

The directives of the Twentieth Congress of the CPSU for the sixth five-year plan for 1956–1960 provide for an increase in coal production in 1960 to 593 million tons, and for the commissioning of the capacity of coal mines and open pits for the extraction of approximately 240 million tons of coal per year.

Such an increase in coal production is associated with an enormous scale of construction of coal enterprises, including new mines, reconstruction, and the opening of new horizons. At present, construction periods are very long, and they need to be reduced by approximately 1.5 times. The actual duration of construction of mines commissioned in recent years is given in Table 1.

Table 1

One of the most important reserves for reducing the construction period of mining enterprises and, in particular, coal mines is the shortening of the duration of the preparatory period, which accounts for 20–30% of the planned period of the entire mine construction. However, insufficient attention is paid to this important question, and the actual duration of the preparatory period sometimes exceeds the planned period for the entire construction.

To accomplish this task, more advanced equipment and organization of production are required for the construction-and-installation work of the preparatory period.

The construction of mining enterprises may be divided into four periods: preliminary, preparatory, main, and finishing-and-liquidation.

The preliminary period of construction is the interval of time from the raising of the question of constructing a mining enterprise to the issuance of the approved design assignment with a summary estimate of the first-

...of routine work of the preparatory period, approval of the title, and opening of financing.

The preparatory period is the interval of time during which all initial organizational measures and first-priority construction-and-installation work are carried out—from receipt of the approved design assignment or technical design with the corresponding documentation up to the start of driving, with full equipment of the main mine workings that open up the mine field.

The main period is the interval of time from the end of the preparatory period to the commissioning of the mining enterprise, including the execution of the entire approved volume of construction-and-installation work and the testing of technological equipment.

The finishing-and-liquidation period is the interval of time during which finishing work is performed after the enterprise has been commissioned, and sometimes second-priority work as well, and the liquidation of the construction organization at the construction site is carried out.

The preparatory period is divided into two stages: the first—initial organizational measures, and the second—the execution of construction-and-installation work. The more completely the work of the preparatory period has been carried out, the more organized, higher-quality, more orderly, less costly, and faster the work of the main period will proceed.

Before 1951, the duration of the preparatory period for mine construction in Kuzbass and Karaganda was adopted without the necessary calculations, most often as 3 months, and in some cases as 6 months. In departmental instructions of 1949, the duration of the preparatory period was established for ordinary construction conditions depending on the volumes of work for preparation for shaft sinking, and in 1948 and 1951 depending on the annual productivity of the mines. Since 1951 the duration of the preparatory period for the construction of individual mines has been justified by calculation.

In 1952, in accordance with a decree of the Government of the USSR and the departmental instructions issued in furtherance of it, for ordinary conditions in settled areas, with a defined set and volume of work, the duration of the preparatory period was set at 6–8 months.

VNIIOmshs, in standard designs for organizing the construction of mines with annual productivity of 600 and 1200 thousand tons, hereinafter referred to as T-600 and T-1200, adopts the same duration of the preparatory period—8 months—regardless of their capacity, cost of construction, volume of work in the preparatory period, depth of shafts, and other factors [4 and 5].

In the designs of Kuzbassgiproshakht for the construction of mines under difficult conditions and with large volumes of work in the preparatory period, its duration in 1952 and 1954 was determined as 12–24 months.

A review of the designs of 20 Kuzbass mines and 11 Karaganda mines showed that the duration of the preparatory period in designs from 1946–1950 was adopted as less than that established by directives and increased sharply in the designs of recent years.

The established dependence of the length of time allotted to the preparatory period on the years in which the designs were compiled is unfounded and, obviously, abnormal.

The distribution of the volumes of work of the preparatory period by months according to two standard designs for organizing mine construction by VNIIOmshs and according to designs of certain Kuzbassgiproshakht mines is presented in the curves of Fig. 1.

The duration of the preparatory period and the designed volume of work for mines with elaborated questions of its organization are evident from Table 2.

The curves in Fig. 1 and Table 2 show that the distribution of work by months of the preparatory period for projects of different

Fig. 1. Volumes of work in the preparatory period by months, by projects: 1—for the standard project of the T-1200 mine; 2—for the standard project of the T-600 mine; 3—for the Kapitalnaya No. 3 mine; 4—for the Karagailinskaya mine; 5—for the Ignatyevskaya mine; 6—for the Baidayevskaya Severnaya mine.

Table 2

¹ For the “Kapitalnaya No. 3” mine, the volume of work is shown according to the design calendar schedule, in which housing construction is not provided for.

mines has two basic schemes. At the T-1200 mines, the “Ignat'evskaya” mine in the Donbass, and the “Baidaevskaya Severnaya” mine in the Kuzbass, the development of work by months was designed with an increase in the volume of work, reaching a maximum in the last month of the preparatory period. At the “Kapital'naya No. 3” and “Karagailinskaya” mines in the Kuzbass and at T-600, the volume of work first increased, reaching in the second quarter a maximum for the “Kapital'naya No. 3” mine, and in the subsequent months and by the beginning of the main period it decreases for the “Kapital'naya No. 3” mine by 1.4 times, for the T-600 mine by 2.2 times, and for the “Karagailinskaya” mine by 1.3 times.

The practice of designing large volumes of work in the first months of the preparatory period is incorrect and unrealistic; it is also incorrect to reduce the volumes of work toward the end of the preparatory period with the necessary reduction of workers and construction mechanization, and with a sharp increase in the volumes of work at the beginning of the main period.

It should be noted that the projects do not sufficiently take into account the conditions of construction in the preparatory period and the possibilities for developing construction-and-installation work by months; specific methods of industrialization and mechanization of construction for the conditions of the preparatory period are not considered, although solutions that are general for all construction are often unsuitable for the preparatory period; in designing the organization of mine construction, there is no established rational direction in the distribution of the volumes of work by months.

There are no standard designs for the organization of construction-and-installation work in the preparatory period, based on modern equipment and organization for different characteristic conditions of mine construction. Therefore, for each mine-construction project all questions of organizing the work of the preparatory period must be resolved individually.

Table 3

Practice in carrying out construction-and-installation work in the preparatory period of mine construction in Kuzbass and its actual duration

The actual fulfillment of the volume of work of the preparatory period for 10 Kuzbass mines put into operation is given in Table 3. From Table 3 it is evident that the actual duration of the preparatory period in the construction of mines with vertical shafts amounts to from 15.6 to 44.5% of the actual construction period, and for adits—from 23.8 to 27.8%.

The actual duration of the preparatory period is, on average, 1.6 times, and for some mines 2.5–3.5 times, greater than that allowed by the standards; only for mine No. 10 (“Tom-Usinskaya 1–2”) is it 1.5 times less.

The actual duration of the fulfillment of the volumes of work of the preparatory period for Kuzbass mines under construction is given in Table 4.

Table 4

The volumes of work actually carried out in the preparatory period most often amount to less than 10% of the volume to be commissioned, instead of 14–19% according to the standards. Consequently, preparation for the production of work in the main period is incomplete, and the construction-and-installation work of the main period begins without proper preparation, since the average actual completed volume of work of the preparatory period amounts to approximately 50% of the calculated value, based on the recommended standard distribution of work volumes.

The duration of the preparatory period for 15 mines under construction is 1.9 times greater than the standard duration.

From the curves in Figs. 2 and 3 it is evident that the actual fulfillment of the volumes of construction-and-installation work in the preparatory period by months is small in comparison with the designed distribution by months according to the standard designs T-600 and T-1200. At some mines, in individual months of the preparatory period, work was not carried out at all or was carried out in insignificant volumes—50 thousand rubles or less.

The exception is mine 10, which, during the preparatory period, carried out larger monthly volumes of work, as is evident from curve 3 in Fig. 2. For mine 11, curves 3 and 6 (Fig. 3) give the distribution of volumes of work according to the design and actual performance, showing that

actual performance of work volumes by months is small in comparison with the design volumes and those recommended by standard designs.

From Table 5 it is evident that in the first years of construction of the mines under consideration, the planned volumes of work were small.

Fig. 2. Volumes of work in the preparatory period by months:
1 — according to standard design T-1200;
2 — according to standard design T-600; actual performance:
3 — for mine 10; 4 — for mine 5;
5 — for mine 4; 6 — for mine 9; 7 — for mine 8.

For most mines, the annual volumes of work in the first year of construction were planned to be less than the average monthly design volumes for the preparatory period—

Table 5

of the preparatory period and considerably less than the approximate annual volumes established by the norms. For five mines, the volumes of work in the second year, and for some mines also the volumes of work in the third year of construction, were planned at less than the average monthly design volumes of work of the preparatory period. Especially insufficient capital investments are planned for the first two years of construction, during which the work of the preparatory period is carried out.

It should be noted that, because of a lack of designs, material and technical resources, and labor, the reduced plans cited were sometimes not fulfilled. For most mines, the volumes of work actually completed in the first and second years of construction were less than planned; and for some mines, the total volumes of work completed in the first three years of construction were less than the volumes of preparatory-period work designed to be completed in 3–6 months.

The exception is mine 10, which, beginning with the first year of construction, carried out large volumes of work.

Fig. 3. Volumes of preparatory-period work by month: 1—according to standard design T-1200; 2—according to standard design T-600; 3—according to the design for mine 11; actual completion: 4—for mine 14; 5—for mine 6; 6—for mine 11; 7—for mine 7.

The planning of capital investments by year for mine construction is carried out incorrectly, since the necessary volumes of work established by the norms and by the design construction schedules are not ensured.

Shortcomings in the Practice of Carrying Out the Preparatory Period

1. In the preparatory period, insufficient use is made of modern equipment and organization of production for construction-and-installation work, the introduction of which is an urgent task for mine-construction organizations.

2. Planning itself predetermines long periods for mine construction and the failure to complete the volumes of work of the preparatory period within the time limits provided by design schedules and directives, since instead of financing the required volume of work of the preparatory period over approximately 8–15 months, it is stretched out over 2–3 years. In their decisions, the Party and the Government of the USSR draw attention to the shortcomings of planning; however, it is improving extremely slowly.

3. Construction-and-installation work by months of the preparatory period of mine construction is carried out in insufficient volumes, is sometimes sharply reduced, and in some months even ceases, owing to the lack of material and technical resources, or lack of preparedness for winter, or as a result of transferring workers to other construction projects.

4. A major shortcoming should be considered the absence of designs that ensure, in the preparatory period:

a) the creation of a construction base that can quickly be put into operation and used in the preparatory period, for example: prefabricated-and-demountable temporary buildings and structures, mobile workshops;

b) a rational technology for carrying out work on the basis of modern equipment, taking into account the shortage, in the first months of the preparatory period, of electric power, as well as its other special features.

1. Insufficient attention is paid in the preparatory period to the construction of motor roads and railways and to their maintenance.

2. The preparatory period of the stage of production of construction-and-installation work begins without proper preparation of the first stage, without its construction-organization design, without checking the availability of financing, material and technical resources and personnel, without coordination with work at other sites of the construction organization. Therefore, the preparatory period begins with small volumes of work, which by months do not give the necessary growth, and sometimes lead to a reduction in the volumes of work and even to their cessation.

The main reasons for the execution of small volumes of work in the first years and by months of the preparatory period, which increase the duration of the preparatory period and the time of the entire construction, are usually not one but several factors, such as: untimely receipt of the necessary design-and-estimate documentation, defective planning of capital investments and insufficient financing, lack of provision with material and technical resources, backwardness of the equipment and organization of work used and a large share of manual labor in construction, the high labor intensity of work as a result of insufficient prefabrication and mechanization, and the insufficiency of the construction base.

Determination of the Duration of the Preparatory Period of Mine Construction

There are no definite methods for determining the duration of the preliminary period and the first stage of the preparatory period.

To determine the duration of the second stage of the preparatory period (the stage of construction-and-installation work), there are three methods:

1. The normative method based on the directives of the Government of the USSR. Standards N 135-56 establish construction durations for certain standard capacities of mines in Kuzbass and other basins.

2. The method of calculating the volumes of work, required resources, and drawing up calendar schedules, as given in construction-organization designs.

3. The formula of engineer Ya. V. Brovman for determining the time required to prepare for shaft sinking and equip the shafts [3, p. 17].

\[ A = 4(1 + 0.001H), \tag{1} \]

where \(A\) is the time for preparing for shaft sinking, months;
\(H\) is the shaft depth, m.

To determine the duration of the second stage of the preparatory period of mine construction, we propose the formula

\[ t_2 = n(1 + mH) + vP + cM, \tag{2} \]

where \(t_2\) is the duration of the second stage of the preparatory period, months;
\(H\) is the shaft depth or adit length, m;
\(m, n\) are coefficients depending on the type of opening workings (vertical shafts, inclined shafts, adits) and on the conditions of driving them, which vary for different basins and even districts;
\(v\) is a coefficient depending on the difficulty of developing the construction sites;
\(P\) is the volume of work in the preparatory period, million rubles;
\(M\) is the capacity of the mine, million tons;
\(c\) is a coefficient depending on the capacity of the mine.

The numerical values of the coefficients recommended by the author are given in Table 6.

Table 6

The numerical values of the coefficients \(m\) and \(n\) were determined on the basis of studying the coefficients adopted by engineer Ya. V. Brovman in formula (1), by checking calculations of the duration of work to prepare for shaft sinking under Kuzbass conditions.

The numerical values of the coefficients in formula (2) were determined on the assumption that, for the construction of Kuzbass mines with a capacity of 600–1200 thousand tons, the duration of the preparatory period under ordinary conditions and with the normative composition and volume of construction-and-installation work should be no more than 25% of the normative construction periods for mines approved in 1956.

The large discrepancies between the standard duration of the preparatory period and the actual duration at the mines of the Kuzbass follow from the shortcomings in the practice of carrying it out, which must be eliminated. The preparatory period at the “Tom-Usinskaya No. 1—2” mine, thanks to special attention to this construction project and to its better provision with the necessary resources, was shorter than the standard one.

Formula (2), which determines the duration of the preparatory period as a function of the factors of shaft depth, mine capacity, the volume of construction-and-installation work of the preparatory period, and the degree of settlement of the district, naturally gives more correct results than those previously adopted on the basis of a single factor, and also than those determined according to the standard duration of mine construction approved in 1956, by the factors of mine capacity, shaft depth, and settlement of the district, but without taking into account the volume of construction-and-installation work of the preparatory period, which has a tendency to increase.

To establish refined coefficients in formula (2) for individual basins and districts, further study is necessary, under different conditions of mine construction, of the execution and duration of the preparatory period.

Schemes for organizing construction in the preparatory period and the main directions for reducing its duration

During the preparatory period, construction-and-installation work may be carried out on: a) temporary buildings and structures; b) permanent buildings and structures used for construction purposes; c) permanent buildings and structures not used for construction purposes; d) priority facilities of general district significance.

According to the time of commencement and the degree of combination of the indicated types of construction-and-installation work, the author has drawn up and examined several schemes. For the schemes shown in Fig. 4, the following basic principles have been adopted.

First of all, priority facilities of general district significance must be built; if there is a prospective plan for developing the deposit, they are erected in the third stage of the preliminary period (Fig. 4a).

The next priority is the organization of the construction base and the erection of the necessary temporary buildings and structures that ensure execution of the work of the preparatory period. Under favorable conditions, organization of this construction may begin in the first stage of the preparatory period, after financing has been arranged in Prombank and land allotments for the construction sites have been formalized (Fig. 4b).

The erection of permanent buildings and structures used for construction begins as soon as possible after preparation of the construction site, by constructing the necessary temporary buildings and structures, priority general-district facilities, and also the mobile construction base.

It is recommended that erection of permanent buildings and structures not used for construction purposes begin at the end of the preparatory period, in order to avoid reducing the achieved volumes of work and in order to use the available construction equipment and labor (Fig. 4c).

It is not recommended that the erection of permanent buildings and structures not used for construction purposes be begun in the first and second thirds of the preparatory period, although in practice this is often done, since the duration of the preparatory period increases.

whereas construction of the main facilities is carried out without sufficient preparation.

A rational direction should be considered the systematic increase in the volume of work performed in the preparatory period from the first month to the subsequent ones, in accordance with the increase in material and technical resources at the construction sites, the provision of housing and power supply, and the equipping of the construction project.

Taking the above into account, the basic principles of the recommended schemes for the composition and combination of work in the preparatory period may be formulated as follows: accelerated but gradual development of work up to the fulfillment of the required monthly volumes; the fullest possible completion of the volumes of work of the preparatory period before the beginning of the main period; prevention of any reduction in monthly volumes of work toward the beginning of the main period; construction of the minimum number of permanent buildings and structures not used for construction purposes.

Fig. 4. Schemes of the composition and time-combination of work in different periods of construction. Designations: $a$, $b$, $v$—schemes; $T_p$—preparatory period; $T_o$—main period; $t''_p$—third stage of the preliminary period; $t_1$—first stage of the preparatory period; $t_2$—second stage of the preparatory period; 1—priority general-site works; 2—temporary buildings and structures; 3—permanent buildings and structures used for construction; 4—permanent buildings and structures not used for construction purposes; 5, 6, 7—outlines of the work of the preliminary, preparatory, and main periods, respectively.

Proper organization of the work of the preparatory period reduces its actual duration by 7–20 months and brings it, under ordinary conditions, down to the time limits established by the standards. Such a reduction in its duration will amount to 20–30% of the reduction required in the duration of the entire construction by a factor of 1.5.

The possibility of sharply reducing the duration of the preparatory period and of the entire construction of mines is confirmed by the practice of constructing individual mines in Kuzbass and in other coal basins.

Among the principal lines of action for reducing the duration of the preparatory period, we distinguish three groups of measures.

The first group of measures, which depend on higher-level organizations, includes: proper planning of annual volumes of work; provision of financing and of the necessary allocated resources in accordance with the calendar schedule of the preparatory period; creation of a construction organization corresponding to the scale of the work; creation of an interdepartmental and departmental modern construction base; establishment of control and responsibility for the time limits, completeness, and quality of performance of the work of the preparatory period.

The second group of measures, which depend on design institutes, includes: a) a well-founded determination of the objects of construction-and-installation work of the preparatory period; timely provision of high-quality design and estimate documentation, with a well-developed section on the organization of work in the preparatory period that meets modern requirements of industrialization and mechanization; development of designs for prefabricated-and-demountable temporary buildings and structures of the mobile own construction base, etc.; b) preparation, for the construction of medium and large mines in inhabited and uninhabited areas, of standard designs for organizing the execution of construction-and-installation work of the preparatory period on the basis of progressive technology, taking into account the specific features of this period.

The third group, dependent on construction organizations, includes, in addition to the obvious provision of material and technical resources, the following measures:

reduction of the labor intensity of construction-and-installation work in the preparatory period by creating a mobile housing stock of prefabricated-and-demountable houses, with the use of tents in individual cases; provision of prefabricated-and-demountable (inventory) industrial buildings and structures; equipping the mobile first-priority own base for repairing equipment and vehicles, manufacturing the necessary prefabricated structural components, producing and extracting local materials; provision of electric power supply and water supply; introduction of the principle of prefabrication for permanent buildings and structures erected in the preparatory period;

provision and maximum utilization of new equipment and organization of mine construction designed and selected for the conditions of the preparatory period with the appropriate comprehensive mechanization;

combining, in time, construction-and-installation work at several construction sites;

systematic increase in the monthly execution of volumes of work in the preparatory period up to the required maximum, with a rational sequence of work, without allowing the reductions—and still less the cessations—of work that occur in construction practice;

maintenance of communication routes and means of transport in good condition;

provision with permanent qualified personnel by securing and training them in order to avoid their turnover.

Construction-and-installation work of the preparatory period should not be begun without checking the provision of design-and-estimate documentation, financing, and material and technical resources.

Conclusions

In designing the organization of the work of the preparatory period, the specific conditions of construction during the preparatory period are insufficiently studied and taken into account; there are no basic guidelines and instructions for designing the organization of work in this period; there are no standard projects for organizing different types of work of the preparatory period on the basis of modern progressive equipment; principles have not been established for distributing work by months of the preparatory period; and the work of the preparatory period is not provided with design-and-estimate documentation in a timely manner and with sufficient completeness.

The practice of carrying out construction-and-installation work in the preparatory period is characterized by the planning of insufficient capital investments for completing within the established time limits the designed and necessary work, by the execution of small volumes of work in the first years of construction, which increases the duration of the preparatory period, and by a large share of manual labor, insufficient industrialization and mechanization of construction.

The actual duration of the preparatory period accounts for about 30% of the actual total construction time of mines, exceeding the established standard time by two to three times and more, and sometimes exceeding the full design time for mine construction.

As a result of the lag in the execution of work of the preparatory period, shaft sinking and the main construction-and-installation work on the surface begin before the completion of the necessary preparatory work, which worsens organization, increases cost, and causes an increase in the construction time of mines.

The volumes of work of the preparatory period tend to increase in order to ensure better preparation for the main period, and also with the introduction of large volumes for the construction of permanent buildings and structures used for shaft sinking and for other construction purposes, which blurs the boundary between the preparatory and main periods.

The preparatory period is an important reserve for reducing the duration of the main period and of construction as a whole, owing to its great actual duration and the increasing importance of the completeness and quality of its implementation.

To reduce the duration of the preparatory period, it is proposed:

1. To carry out the measures indicated in the basic guidelines for reducing the duration of the preparatory period, reducing by all means the labor intensity of construction-and-installation work, and, taking specific conditions into account, implementing the possible comprehensive mechanization and industrialization of work.

2. To establish the correct sequence of work in the preparatory period, one that with each month facilitates the production and development of work.

3. To draw up an instruction for designing the section on the organization of construction in the preparatory period, taking as a basis the proposed—

… by the author in the dissertation [6], as well as the latest instructions for carrying out work in the preparatory period of mine construction.

4. Create the necessary lead in design work so that the preparatory period of mine construction begins with complete design-and-estimate documentation, making it possible to plan and organize the work correctly. This requires expanding the design of standard mine projects and introducing them into construction.

5. The construction of a blocked surface complex and of deep mines is associated with the tendency to use permanent buildings, structures, and equipment for driving the workings that open up the mine field.

Such construction can be carried out if working designs are available that make it possible, in advance, during the preliminary period, to place orders for the necessary permanent equipment and prefabricated building components and structures, and during the preparatory period to erect the required permanent buildings and structures, as well as to receive and install in them the permanent equipment to be used.

6. Make extensive use of specialized organizations for the construction of motor roads and railways, bridges, and electric-power supply.

REFERENCES

1. Balbachan Ya. I. Ways of accelerating mine construction, MT i GE, No. 8, August, pp. 10–14, 1955.

2. Brovman Ya. V. Reducing the construction time of coal mines. Ugol’, No. 5, May, pp. 25–27, 1952.

3. Brovman Ya. V. A method for determining the duration of construction of coal mines, Ugol’, No. 1, January, pp. 16–19, 1953.

4. VNIIOMShS. Standard project for organizing the construction of a mine with a capacity of 600 thousand tons of coal per year. Ugletekhizdat, 1953.

5. VNIIOMShS. Standard project for organizing the construction of a mine with a capacity of 1200 thousand tons of coal per year. Ugletekhizdat, 1953.

6. Leont’ev S. N. Basic questions of organizing mine construction in the preparatory period under the conditions of the Kuzbass. Dissertation, 1956.