CN107273636B - Method for evaluating rationality of support of anchor rod cable of soft coal rock at deep coal seam roadway side - Google Patents
Method for evaluating rationality of support of anchor rod cable of soft coal rock at deep coal seam roadway side Download PDFInfo
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Abstract
The invention relates to a method for evaluating the support rationality of a soft coal rock anchor cable at a deep coal seam roadway side, wherein the support rationality can be evaluated by reflecting the deformation velocity coefficient value at a constant velocity stage. On the basis of determining reasonable values of deformation speeds in constant-speed stages when bearing capacity of coal rocks in different sections is fully exerted, deformation characteristics of a bolt anchoring area, an anchor rope anchoring area and soft coal rocks outside the anchoring area of a deep coal seam roadway side part along with time evolution can be monitored in engineering, deformation speed coefficients of the soft coal rocks in the constant-speed stages in the different sections are analyzed and compared with reasonable values to evaluate the rationality of bolt and anchor rope support parameters, and reasonable support parameters are determined. The support rationality can be judged in the early stage of coal rock deformation, support parameters can be adjusted in time, and the support cost is the lowest on the basis of ensuring safety.
Description
Technical Field
The invention relates to the field of reasonable support of deep coal seam tunnels, in particular to a method for evaluating the support rationality of a soft coal rock anchor rope at a deep coal seam tunnel side.
Background
More than 70% of deep tunnels are arranged in a coal seam, because two sides of the tunnels are soft coal rocks, the tunnel is generally unstable locally at the sides of the tunnels in engineering, so that the overall instability of the tunnels is caused, and the selection of reasonable support to maintain the deformation stability of the soft coal rocks is important for the efficient and continuous mining of deep coal. As shown in fig. 1, at present, a prestressed anchor rod is often arranged in soft coal rocks with a certain thickness on the surface layer of the roadway slope part to form an anchor rod compression arch, a prestressed anchor cable is arranged in a larger thickness range of the roadway slope part to form an anchor cable compression arch, and the anchor rod compression arch and the anchor cable compression arch jointly act or simultaneously assist the support of metal support shed legs and the like to keep the deformation stability of the soft coal rocks of the slope part. Due to the complexity of occurrence conditions of the deep coal seam, the reasonability of support parameters of anchor rods and anchor cables of the deep coal seam roadway side part is difficult to achieve through complete quantification determination, support parameters of the anchor rods and the anchor cables of the roadway side part are selected mainly according to theoretical analysis, numerical simulation and engineering experience at present, the expected effect is difficult to achieve, and deformation of the soft coal rock of the supported deep coal seam roadway side part possibly still has a 'destabilization' trend.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for evaluating the support rationality and determining reasonable support parameters of the soft coal rock anchor rods and the anchor cables at the side parts of the deep coal seam roadway, which is simple, reasonable, easy to implement and high in accuracy.
In order to solve the technical problems, the technical solution of the invention is as follows: a simple and convenient engineering actual measurement method is used for evaluating the rationality of support parameters of a soft coal rock anchor rod and an anchor cable at the deep coal seam roadway side part, and the determination of the support parameters of the reasonable anchor rod and the anchor cable has engineering practical value.
The deformation delta (t) of the soft coal rock anchor rod anchoring area, the anchor cable anchoring area and the outer soft coal rock deformation delta (t) of the anchoring area of the deep coal seam roadway side part mainly presents three stages along with the change of time t:
(1) deceleration phase
A1To reflect the amount of deformation during the deceleration phase, B1Coefficient reflecting degree of attenuation of deformation speed in deceleration stage, t1The deformation action time of the soft coal rock in the deceleration stage is shown.
(2) Constant velocity phase
λ is the deformation velocity coefficient at constant velocity stage of each section, t2The deformation action time of each section in the constant speed stage is shown.
(3) The constant velocity stage is developed to the acceleration stage and is unstable or is converted to the deceleration stage again to be stable.
The research shows that: reasonable support needs to ensure that the deformation of the anchor rod anchoring area, the anchor cable anchoring area and the soft coal rock outside the anchoring area is stable, and simultaneously, the bearing capacity of the soft coal rock in each section is fully exertedAnd the supporting cost is lowest. The support rationality can be evaluated by reflecting the value of the deformation speed coefficient lambda in the constant speed stage. Reasonable value lambda of deformation speed at constant speed stage when determining that the bearing capacity of soft coal rock in different sections is fully exerted1 reasonable、λ2 reasonable、λ3 reasonableOn the basis, the evolution characteristics of the deformation delta (t) of the soft coal rock anchor rod anchoring area, the anchor cable anchoring area and the soft coal rock outside the anchoring area at the side part of the deep coal seam tunnel along with the time t can be monitored in engineering, and the deformation speed coefficient lambda of the soft coal rock at the constant speed stage can be analyzed1、λ2、λ3And is connected to λ1 reasonable、λ2 reasonable、λ3 reasonableAnd evaluating the rationality of the support parameters of the anchor rods and the anchor cables and determining the reasonable support parameters. The support rationality can be judged in the early stage of coal rock deformation, and support parameters can be adjusted in time, so that the support cost is the lowest on the basis of ensuring safety.
The method mainly aims at a rectangular or trapezoidal roadway of a deep coal seam, the burial depth of the roadway is generally 700.0-1100.0 m, the lithologic binding power of coal rock is 0.6-1.2 MPa, and the internal friction angle is 18-28 degrees, and the method comprises the following steps:
(1) as shown in fig. 2, holes are drilled at key parts which are easy to destabilize at two sides of a deep coal seam roadway, and the drilling depth exceeds the range of surrounding rocks and enters the original rocks, generally exceeds 10.0 m; aiming at a rectangular or trapezoidal tunnel of a deep coal seam, the key part easy to destabilize is the middle part of two sides of the tunnel.
(2) Arranging a multipoint displacement meter in the drilled hole at different distances r from the surface of the roadway1、r2、r3The first fluke, the second fluke and the third fluke are arranged in the position. The length of the anchor rod, the length of the anchor cable and the loosening and crushing range of the soft coal rock at the roadway side part are respectively L1、L2、L3Wherein the measuring point B is located in the anchor rod anchoring area, r1≈L1(ii) a The measuring point C is positioned outside the anchor rod anchoring area in the anchor cable anchoring area, r2≈L2(ii) a The measuring point D is positioned in the original rock outside the surrounding rock range of the roadway wall part, r3>L3。
(3) Recording the elongation delta l of a first steel wire rope connected with a first fluke at different moments t1(t) connecting the second flukeElongation of the second wire rope is Deltal2(t) the elongation of the third wire rope connecting the third fluke is Deltal3(t)。
(4) Defining the deformation of the anchor rod anchoring area, the anchor cable anchoring area and the weak coal rock outside the anchoring area at different moments t as delta1(t)、△2(t)、△3(t) of (d). And calculating Δ1(t)、△2(t)、△3The (t) values are respectively Δ1(t)＝△l1(t)，△2(t)＝△l2(t)-△l1(t)，△3(t)＝△l3(t)-△l2(t)。
(5) According to Δ1(t)、△2(t)、△3And (t) performing regression analysis on the deformation deceleration stage and the constant speed stage delta (t) of each section weak coal rock along with the evolution of the time t according to the actual measurement result of the value (t).
The regression equation of the deceleration stage of the deformation of the soft coal rock in each section along with the change of time can be shown as follows:
A1to reflect the amount of deformation during the deceleration phase, B1Coefficient reflecting degree of attenuation of deformation speed in deceleration stage, t1The deformation action time of the soft coal rock in the deceleration stage is shown.
Secondly, the constant velocity stage regression equation of the deformation of the soft coal rock in each section along with the change of time can be shown as follows:
λ is the deformation velocity coefficient at constant velocity stage of each section, t2The deformation action time of each section in the constant speed stage is shown.
(6) Determining the reflection delta according to the regression analysis result1(t)、△2(t)、△3(t) constant velocity stage deformation velocity factor lambda as a function of time t1、λ2、λ3. In particular if weak coal petrography is deformed over timeThe evolution exhibits only a deceleration phase and tends to stabilize, which can be considered as λ ═ 0.
(7) According to the numerical simulation and a large number of engineering actual measurement results, the deformation speed value of the soft and weak coal rock at the constant speed stage is determined to be lambda when the bearing capacity of the soft and weak coal rock in each section is fully exerted1 reasonable1.0 mm/day, lambda2 reasonable1.5 mm/day, lambda3 reasonable2.0 mm/day.
(8) The deformation speed coefficient lambda which is obtained by regression analysis and reflects the constant speed stage of the soft coal rock in each section1、λ2、λ3Respectively corresponding to the deformation speed reasonable value lambda of each section of weak coal rock at constant speed stage1 reasonable1.0 mm/day, lambda2 reasonable1.5 mm/day, lambda3 reasonableAnd (3) comparing the parameters 2.0 mm/day, determining the rationality of the support parameters of the anchor rods and the anchor cables according to the table 1, and adjusting the support parameters in time.
TABLE 1
(9) The deformation of the soft coal rock in about 25 days after deep coal seam roadway excavation is converted into the constant speed stage from the deceleration stage, although the duration of the constant speed deformation stage is longer, the deformation speed coefficient lambda of each section in the constant speed stage can be determined within 5-10 days at the initial stage of the constant speed deformation stage1、λ2、λ3Namely, the support rationality can be judged 30-35 days in the early stage of coal rock deformation, and support parameters can be adjusted in time, so that the support cost is reduced while the safety is ensured.
Compared with the prior art, the invention has the advantages that:
(1) the invention provides a method for quantitatively evaluating the support rationality of a soft coal rock anchor cable at a deep coal seam roadway side;
(2) the invention is simple to operate and easy to implement in engineering;
(3) according to the invention, the support rationality can be judged in the early stage of the deformation of the weak coal rock of the deep coal seam roadway, the support parameter can be adjusted in time, the repair caused by the instability in the later stage of the deformation of the coal rock is avoided, the safe, reliable and quick tunneling of the roadway is ensured, and the method has obvious economic benefits and good popularization and application prospects.
Drawings
FIG. 1 is a layout diagram of soft coal rock anchor rods and anchor cables on two sides of a deep coal seam roadway;
FIG. 2 is a schematic diagram of arrangement of a multi-point displacement meter and drill holes at key parts of two-side weak coal rocks of a deep coal seam roadway, which are prone to instability;
FIG. 3 is a curve of the deformation of soft and weak coal rock anchor rods at two sides, anchor cable anchor zones and the soft and weak coal rock outside the anchor zones evolving with time in a deep coal seam tunnel actually measured by engineering, wherein (a) the anchor rods anchor zones, (b) the anchor cable anchor zones, (c) the soft and weak coal rock outside the anchor zones;
fig. 4 is a layout diagram of the adjusted soft coal rock anchor rods and anchor cables at the deep coal seam roadway side.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
In order to quantitatively evaluate the support rationality of the soft coal rock anchor rod and the anchor cable at the deep coal seam roadway side part and further adjust the support parameters of the anchor rod and the anchor cable in time, the invention provides a method for evaluating the support rationality of the soft coal rock anchor rod and the anchor cable at the deep coal seam roadway side part, which comprises the following main steps of:
(1) as shown in fig. 2, holes are drilled at key parts which are easy to destabilize at two sides of a deep coal seam roadway, and the drilling depth exceeds the range of surrounding rocks and enters the original rocks, generally exceeds 10.0 m; aiming at a rectangular or trapezoidal tunnel of a deep coal seam, the key part easy to destabilize is the middle part of two sides of the tunnel. Further, theoretical analysis, numerical simulation and a large number of engineering practices all show that: when the distance between two soft coal rocks of two sides of the deep coal seam roadway and the surface of the roadway exceeds 10.0m, the displacement is very small and is approximately zero; as shown in figure 2, the loosening crushing range and the crushing degree of the AB part in the middle of two sides of the roadway are the most obvious, and the key point for evaluating the support rationality of the anchor rod and the anchor cable at the part and keeping the coal rock stability of the part is the most important.
(2) Arranging multipoint displacement meters at the positions of the drill holes A, B, C and D and at different distances r from the surface of the roadway1、r2、r3The first fluke 1.1, the second fluke 1.2 and the third fluke 1.3 are positioned. Defining anchor length, anchorThe cable length and the loosening and crushing range of the roadway side part are respectively L1、L2、L3Wherein the measuring point B is positioned at the end part of the anchor rod anchoring area r1≈L1(ii) a The measuring point C is positioned at the end part of the anchoring area of the anchor cable outside the anchoring area of the anchor rod, r2≈L2(ii) a The measuring point D is positioned in the original rock outside the surrounding rock range of the roadway wall part, r3>L3。
(3) Recording the elongation delta l of a first wire rope 2.1 connected with a first fluke 1.1 at different times t1(t) the elongation of the second wire rope 2.2 connecting the second fluke 1.2 is Deltal2(t) the elongation of the third wire rope 2.3 connecting the third fluke 1.3 is Deltal3(t)。
(4) Defining the deformation of the anchor rod anchoring area, the anchor cable anchoring area and the weak coal rock outside the anchoring area at different moments t as delta1(t)、△2(t)、△3(t) of (d). Furthermore, because the first fluke 1.1, the second fluke 1.2 and the third fluke 1.3 are respectively positioned in the original rock outside the range of the surrounding rock of the anchor rod anchoring end, the anchor cable anchoring end and the upper part, the delta can be calculated1(t)、△2(t)、△3The (t) values are respectively Δ1(t)＝△l1(t)，△2(t)＝△l2(t)-△l1(t)，△3(t)＝△l3(t)-△l2(t)。
(5) According to Δ1(t)、△2(t)、△3And (t) performing regression analysis on the deformation delta (t) of the weak coal rock at the deceleration stage and the constant speed stage of each section along with the evolution of the time t according to the actual measurement result of the value (t).
The regression equation of the deceleration stage of the deformation of the soft coal rock in each section along with the change of time can be shown as follows:
A1to reflect the amount of deformation during the deceleration phase, B1Is a coefficient reflecting the degree of attenuation of the deformation speed in the deceleration stage.
Secondly, the constant velocity stage regression equation of the deformation of the soft coal rock in each section along with the change of time can be shown as follows:
and lambda is the deformation speed coefficient of each section in the constant speed stage.
The regression equation is obtained by theoretical analysis, numerical simulation and a large amount of engineering practice, and the correlation coefficient of the regression equation under different conditions reaches more than 0.9. Deformation delta of weak coal rock in each section according to different time t1(t)、△2(t)、△3(t) calculating the actual measurement result by using a least square method to obtain a correlation coefficient A1、B1Lambda value.
(6) Determining the reflection delta according to the regression analysis result1(t)、△2(t)、△3(t) deformation velocity coefficient lambda of weak coal rock at constant velocity stage along with time t change1、λ2、λ3. In particular, if the deformation of the weak coal rock only exhibits a deceleration stage and tends to be stable over time, λ may be considered to be 0.
(7) Determining reasonable value lambda of deformation speed coefficient at constant speed stage when the bearing capacity of soft coal rock of each section is fully exerted according to numerical simulation and a large number of actual measurement results of engineering1 reasonable1.0 mm/day, lambda2 reasonable1.5 mm/day and λ3 reasonable2.0 mm/day. Analysis shows that the bearing capacity exertion of the weak coal rocks in different sections is obviously related to the deformation speed in the constant speed stage, and the correlation between the deformation speed coefficient lambda and the bearing capacity exertion degree of the weak coal rocks in the constant speed stage under different conditions is analyzed by establishing a creep numerical calculation model capable of better reflecting the deformation acceleration stage of the weak coal rocks; aiming at a deep coal bed rectangular or trapezoidal tunnel with the buried depth of 700.0-1100.0 m, the coal rock lithology of 0.6-1.2 MPa and the internal friction angle of 18-28 degrees, according to numerical simulation and combination of a large number of engineering actual measurement results, reasonable values of the deformation speed coefficients of weak coal rocks at different sections at constant speed stages can be taken1 reasonable1.0 mm/day, lambda2 reasonable1.5 mm/day and λ3 reasonable2.0 mm/day.
(8) Reflecting weak coal rocks of each section obtained by regression analysisDeformation velocity coefficient lambda of deformation constant velocity stage1、λ2、λ3Corresponding to reasonable value lambda of deformation speed coefficient in constant speed stage1 reasonable1.0 mm/day, lambda2 reasonable1.5 mm/day and λ3 reasonableAnd (3) determining the bearing capacity exertion degree of the soft coal rock outside the anchor rod anchoring area, the anchor cable anchoring area and the anchor cable anchoring area according to the following table 1, judging the rationality of the support parameters of the anchor rod and the anchor cable and adjusting the support parameters in time when comparing the parameters of 2.0 mm/day.
TABLE 1
(9) The deformation of the soft coal rock in about 25 days after deep coal seam roadway excavation is converted into the constant speed stage from the deceleration stage, although the duration of the constant speed deformation stage is longer, the deformation speed coefficient lambda of the soft coal rock in the constant speed stage of each section can be determined within 5-10 days at the initial stage of the constant speed deformation stage1、λ2、λ3Namely, the support rationality can be judged 30-35 days in the early stage of coal rock deformation, and support parameter adjustment can be carried out in time, so that the repair caused by instability in the later stage of coal rock deformation is avoided.
The following description is made with reference to specific engineering examples.
Taking a coal seam of a certain mining area of a new mining area of Huainan as an example: the depth of the tunnel is about 900.0m, the two sides are soft coal rocks, the binding power c of the coal rocks is 1.0MPa, and the internal friction angle is
The elastic modulus E is 1.4GPa, the Poisson ratio lambda is 0.34, the section of the rectangular tunnel is 5.0m multiplied by 4.0m, and the top plate and the two sides of the tunnel are supported by anchor rods and anchor cables. The method mainly evaluates the support parameter rationality of the roadway two-side soft coal rock anchor rods and anchor cables, the roadway two-side anchor rods and anchor cables are arranged as shown in figure 1, wherein the support parameters of the upper and lower anchor cables 1 are processed by phi 21.8mm steel strands, the length of the anchor cables is 4100mm, the interval row spacing is 700 multiplied by 700mm, the support parameters of the central anchor cable 2 are processed by phi 21.8mm steel strands, the length of the anchor cables is 4100mm, the interval row spacing is 600 multiplied by 600mm, and each anchor cable is in pre-responseThe force is not less than 160 kN/root; the specification of the central anchor rod 3 is phi 22 multiplied by 2500mm, the row spacing between the anchor rods is 300 multiplied by 300mm, the specification of the upper and lower anchor rods 4 is phi 22 multiplied by 2500mm, the row spacing between the anchor rods is 350 multiplied by 350mm, and the torque of each anchor rod is not less than 260 N.m; the supporting conditions of the anchor cables and the anchor rods on the two sides of the roadway are symmetrical about a central line 5 of the roadway; the width b of the roadway is 5000mm, and the height h of the roadway is 4000 mm. As shown in figure 2, holes are drilled in the OA direction in the middle of two sides of the roadway, the drilling depth is 11.0m, and the distance L between the drilled holes and the surface O point is1＝2.5m、L2＝4.1m、L3At position B, C, D of 10.0m, i.e. at the anchor rod end position, anchor cable end position and in the coal rock raw rock, a multipoint displacement meter is arranged. Deformation delta of anchor rod anchoring area, anchor cable anchoring area and soft coal rock outside anchoring area obtained according to actual measurement result of multipoint displacement meter recorder 3.11(t)、△2(t)、△3The (t) evolution over time t is shown in fig. 3.
(1) Anchor bolt support parameter rationality evaluation
The regression equation of the deformation of the weak coal rock in the anchoring area along with the evolution of time is as follows:
△＝28.02(1-e-0.0915t)
the deformation of the soft coal rock tends to be stable after only showing a deceleration stage along with the time evolution, and the lambda is1＝0，λ≤0.8λ1 reasonableAnd the bolt spacing is increased if the bolt support parameters are not reasonable.
(2) Evaluation of rationality of anchor cable support parameters
Firstly, the regression equation of the deformation of the weak coal rock in the anchor cable anchoring area along with the evolution of time is as follows:
△＝59.38(1-e-0.0438t)t≤25
△＝38+1.6(t-25)t≥25
deformation velocity coefficient lambda of deep weak coal rock in constant velocity stage21.6 mm/day, 1.2 lambda2 reasonable≥λ2≥0.8λ2 reasonableAnd the anchor cable anchoring area bears reasonably.
Secondly, the regression equation of the deformation of the soft coal rock outside the anchor cable anchoring area along with the evolution of time is as follows:
△＝55.2(1-e-0.04941t)t≤25
△＝38+3.0(t-25)t≥25
deformation velocity coefficient lambda of deep weak coal rock in constant velocity stage33.0 mm/day, lambda3≥1.2λ3 reasonable. And (4) the length of the anchor cable is increased if the anchor cable support parameters are unreasonable.
(3) Anchor rod and anchor cable support parameter adjustment
Adjusting support parameters of anchor cables and anchor rods at two sides of the roadway: the lengths of the anchor cables 1 on the upper side and the lower side and the center anchor cable 2 on the central anchor cable are increased to 6000mm from 4100 mm; the pitch of the central anchor rods 3 is increased from 300 multiplied by 300mm to 500 multiplied by 500mm, the pitch of the upper and lower anchor rods 4 is increased from 350 multiplied by 350mm to 500 multiplied by 500mm, uniform anchor rods 6 with equal pitch are obtained, and other parameters are unchanged; the width b and height h of the roadway are not adjusted, and are 5000mm and 4000mm respectively. The arrangement of the adjusted deep coal seam roadway side soft coal rock anchor rods and anchor cables is shown in figure 4.
The above examples are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims. Various equivalent substitutions and modifications can be made without departing from the spirit and principles of the invention, and are intended to be within the scope of the invention.
Claims (1)
1. A method for evaluating the support rationality of a soft coal rock anchor cable at a deep coal seam roadway side is characterized by comprising the following steps:
(1) drilling holes at key parts prone to instability of two sides of a deep coal seam roadway, wherein the drilling depth exceeds the range of surrounding rocks and enters into original rocks, and the key parts prone to instability are the middle parts of the two sides of the roadway;
(2) arranging a multipoint displacement meter in the drilled hole at different distances r from the surface of the roadway1、r2、r3The first fluke, the second fluke and the third fluke are arranged at the positions, and the length of the anchor rod, the length of the anchor cable and the loosening and crushing range of the roadway wall part are respectively defined to be L1、L2、L3Wherein the first fluke is positioned at the end part of the anchor rod anchoring area as a measuring point B, the action range of the anchor rod is the anchor rod anchoring area, r1≈L1(ii) a The second fluke is used as a measuring point C and is positioned at the anchor cable anchoring area end outside the anchor rod anchoring areaAnd the range of the anchor cable anchoring area subtracting the anchor rod action from the range of the anchor cable action is the anchor cable anchoring area r2≈L2(ii) a A third anchor fluke as a measuring point D is positioned in the original rock outside the surrounding rock range of the roadway wall part, namely outside the anchoring area, r3＞L3；
(3) Measuring the elongation delta l of a first steel wire rope connected with a first fluke at different moments t1(t) the elongation of the second wire rope connecting the second fluke is Deltal2(t) the elongation of the third wire rope connecting the third anchor fluke is Deltal3(t)；
(4) Based on different time t, the deformation of the anchor rod anchoring area, the anchor cable anchoring area and the weak coal rock outside the anchoring area is delta1(t)、Δ2(t)、Δ3(t), the first fluke, the second fluke and the third fluke are respectively positioned in the original rocks outside the range of the anchoring end of the anchor rod, the anchoring end of the anchor cable and the surrounding rocks of the upper part, and delta is calculated1(t)、Δ2(t)、Δ3(t) values are respectively Delta1(t)＝Δl1(t)，Δ2(t)＝Δl2(t)-Δl1(t)，Δ3(t)＝Δl3(t)-Δl2(t)；
(5) According to Δ1(t)、Δ2(t)、Δ3(t) carrying out regression analysis on the deformation delta (t) of the soft coal rock of each section, namely the anchor rod anchoring area, the anchor cable anchoring area, the external deceleration stage of the anchoring area and the constant speed stage, along with the evolution of the time t:
the deceleration stage is that the deformation speed of each section of weak coal rock evolves along with time to meet the following conditions:
①
A1to reflect the amount of deformation during the deceleration phase, B1The coefficient is used for reflecting the attenuation degree of the deformation speed in the deceleration stage;
the constant speed stage is that the deformation speed of each section of weak coal rock evolves along with time to meet the following conditions:
②
lambda is the deformation speed coefficient of each section at the constant speed stage;
(6) determining a reflection Delta from the regression analysis result1(t)、Δ2(t)、Δ3(t) constant velocity stage weak coal rock deformation velocity coefficient lambda varying with time t1、λ2、λ3If the deformation of the weak coal rock only presents a deceleration stage and tends to be stable along with the evolution of time, considering that lambda is 0;
(7) determining reasonable value lambda of deformation speed coefficient at constant speed stage when bearing capacity of anchor rod anchoring area, anchor cable anchoring area and soft coal rock outside anchoring area of each section are fully exerted1 reasonable、λ2 reasonable、λ3 reasonable；
(8) The deformation speed coefficient lambda which is obtained by regression analysis and reflects the constant speed stage of deformation of each section, namely the anchor rod anchoring area, the anchor cable anchoring area and the soft coal rock outside the anchoring area1、λ2、λ3Corresponding to reasonable value lambda of deformation speed coefficient in constant speed stage1 reasonable、λ2 reasonable、λ3 reasonableComparing, determining the bearing capacity of the anchor rod anchoring area, the bearing capacity of the anchor cable anchoring area and the exerting degree of the bearing capacity of the weak coal rock outside the anchoring area, judging the rationality of the support parameters of the anchor rod and the anchor cable and adjusting the support parameters in time;
if λ1Greater than λ1 reasonableThe upper limit of the range is that the row spacing between the anchor rods is reduced on the premise that the pretightening force of the anchor rods meets the requirement; if λ1Less than λ1 reasonableThe lower limit of the range is that the row spacing between the anchor rods is increased on the premise that the pretightening force of the anchor rods meets the requirement; if λ2Greater than λ2 reasonableThe upper limit of the range is that the row spacing between the anchor cables is reduced on the premise that the pretightening force of the anchor cables meets the requirement; if λ2Less than λ2 reasonableThe lower limit of the range is that the row spacing between the anchor cables is increased on the premise that the pretightening force of the anchor cables meets the requirement; if λ3Greater than λ3 reasonableThe upper limit of the range is that the length of the anchor cable is reduced on the premise that the pretightening force of the anchor cable meets the requirement; if λ3Less than λ3 reasonableThe lower limit of the range is the pre-tightening force of the anchor cableThe length of the anchor cable is increased on the premise of meeting the requirements;
the depth in the step (1) exceeds 10.0 m; the roadway is a deep coal bed rectangular or trapezoidal roadway;
in the step (7), the lambda is determined according to the numerical simulation and a large number of engineering actual measurement results1 reasonableLambda is equal to (0.8-1.2) mm/day2 reasonableLambda is equal to (1.2-1.8) mm/day3 reasonable(1.6-2.4) mm/day.
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