CN113010956B - Design optimization method of prestressed anchor cable in anchor-pull type retaining structure - Google Patents
Design optimization method of prestressed anchor cable in anchor-pull type retaining structure Download PDFInfo
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Abstract
The invention discloses a design optimization method of a prestressed anchor Cable in an anchor-pulling type retaining structure, which introduces FLAC3D numerical simulation into the traditional prestressed anchor Cable design process, and enables a load-displacement curve obtained in the process of pulling the prestressed anchor Cable obtained by the numerical simulation to approach a load-displacement curve obtained by a field pulling test by adjusting slurry binding power parameters of a Cable unit, so that more accurate rock-soil body-slurry bonding strength can be obtained, and the defects of over-conservative design and engineering material waste caused by taking the lower limit of a reference value interval as the ultimate bonding strength in the traditional design method are overcome. The method combines FLAC3D numerical simulation and field drawing test results, can greatly reduce the frequency of the field drawing test of the prestressed anchor cable, can carry out parameter analysis based on more accurate rock-soil body-slurry bonding strength of different soil layers obtained by optimization, and has important significance for further optimizing the prestressed anchor cable design scheme and reducing the engineering cost.
Description
Technical Field
The invention belongs to the field of geotechnical engineering, and particularly relates to a design optimization method of a prestressed anchor cable in an anchor-pull type retaining structure.
Background
The prestressed anchor cable reinforcing technology is an anchoring technology which fixes anchor cables inside a rock-soil body through grouting in holes and reinforces the rock-soil body by applying prestress through stretching. Because the anchor cable (rod) support system has the advantages of fully adjusting and improving the self strength and self-stability of rock-soil mass, reducing the dead weight of the support structure, ensuring the safety and stability of construction and the like, the anchor cable (rod) support system is generally combined with a retaining structure and is widely applied to foundation pit support.
In recent years, the technology of the prestressed anchor cable has also made certain progress and development: the Chinese utility model patent (grant publication No. CN211816221U) discloses a pressure type shock-absorbing energy-dissipating pre-stressed anchor cable structure, which has the advantages of simple structure, convenient use and good effect; the Chinese utility model patent (grant publication No. CN211819458U) discloses a buffering prestressed anchor cable, which has the advantages of high anti-seismic capacity, long service life, small damage degree to surrounding rocks and high engineering safety; the Chinese invention patent (application publication No. CN111749246A) discloses a method for installing a prestressed anchor cable in a water-rich sand layer, which can effectively eliminate the influence of environmental and geological factors on the stability of the installed anchor cable in the installation process.
The prestressed anchor cable design can be roughly divided into five links of engineering information acquisition, primary design, drawing test verification, secondary optimization design and fixed case implementation, wherein the determination of the anchoring length is a vital design calculation part. At present, the optimization of the design of the prestressed anchor cable is established on the basis of the existing anchor cable design calculation method, and is mainly optimized and explored around two aspects of a design flow and design parameters, the optimization aims to obtain more accurate ultimate bearing capacity of the anchor cable through calculation, and finally, the anchor cable reinforcement scheme can be designed and can take safety and economy into consideration.
However, in the existing prestressed anchor cable design method, the ultimate bonding strength between the prestressed anchor cable anchoring section and the soil layer is usually the lower limit of the reference value interval of the ultimate bonding strengths of different soil layers in the specification, so that the anchoring length value is large, the design is over conservative, and the engineering cost is not saved. In addition, the field drawing test is only used for verifying whether the primarily designed scheme meets the requirement of the ultimate bearing capacity, and quantitative relation is not established with the optimization of the design scheme, so that the value of the field drawing test result is not fully exerted, and the high-quality development concept is contradicted.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a design optimization method of a prestressed anchor cable in an anchor-pull type retaining structure, which can obtain relatively more accurate bonding strength between rock and soil mass and slurry, thereby providing an effective means for fully utilizing field drawing test results, saving engineering cost and implementing a high-quality development concept in the design optimization process of the prestressed anchor cable.
The invention adopts the following technical scheme:
a design optimization method of a prestressed anchor cable in an anchor-pull type retaining structure comprises the following steps:
(1) knowing engineering details, developing engineering geological exploration and rock-soil body mechanical tests to obtain soil layer information and basic physical mechanical parameters required by the design optimization of the prestressed anchor cable; the soil layer information and the basic physical mechanical parameters mainly comprise soil layer names, soil layer thicknesses, compression moduli, Poisson ratios, volume moduli, shear moduli, internal friction angles, cohesive force and densities;
(2) calculating the anchor pulling load required by meeting the stability of rock and soil mass and structural objects; during specific calculation, the anchor-pull type retaining structure is decomposed into a soil retaining structure and an anchor-pull structure to be analyzed respectively; the method for calculating the anchor pulling load can adopt any one of a beam simulation method, a soil pressure distribution method and an elastic fulcrum method;
(3) determining the arrangement and installation angle of a prestressed anchor cable based on the condition of a nearby building and the position of an anchoring stratum; the arrangement of the prestressed anchor cables mainly comprises the contents of the horizontal spacing and the vertical spacing of the prestressed anchor cables, the thickness of a soil layer on the anchoring sections and the arrangement of the soil layer on the anchoring sections; the horizontal spacing of the prestressed anchor cables is at least 1.5m, the vertical spacing is at least 2.0m, the thickness of a soil layer on the anchoring section is at least 4.0m, and the soil layer arranged on the anchoring section is preferably a soil layer with higher bonding strength; the installation angle of the prestressed anchor cable is 10-45 degrees;
(4) calculating the bearing capacity required to be provided by the prestressed anchor cable; the bearing capacity required to be provided by the prestressed anchor cable is calculated by adopting the following formula:
in the formula: n is a radical of hydrogenkThe bearing force required for the prestressed anchor cable, FhS is the horizontal distance of the prestressed anchor cables, b is the required anchor pulling load for stabilizing rock-soil mass and structureaCalculating the width for the structure, wherein alpha is the installation angle of the prestressed anchor cable;
(5) performing initial design on a prestressed anchor cable body, wherein the main content is to determine the type of the prestressed anchor cable, the safety coefficient, the diameter of the anchor cable body and the mechanical property of an anchoring stratum; the types of the prestressed anchor cables are divided into a tension type, a pressure type, a tension dispersion type, a pressure dispersion type and a tension and pressure dispersion type according to the stress state of the anchoring section structure; the safety coefficient of the prestressed anchor cable mainly comprises an anchoring body anti-pulling safety coefficient and a rib body tensile safety coefficient; the diameter of the anchor cable body is preferably 10 cm-15 cm; the mechanical properties of the anchoring stratum comprise the cohesive force between mortar and a prestressed anchor cable and a soil layer comprehensive friction angle;
(6) carrying out a pre-stressed anchor cable field drawing test; the instrument required by the test mainly comprises a drilling machine, an electric oil pump, a hydraulic feed-through jack loading system, a steel strand elongation measuring device, a total station and a grouting machine; the operation in the test implementation process comprises drilling hole forming, prestressed anchor cable installation, grouting, loading and drawing and whole-process test data recording; at least 2 groups of prestressed anchor cable field drawing tests are carried out;
(7) the method comprises the steps that FLAC3D software is adopted to simulate a prestressed anchor cable field drawing test, and a prestressed anchor cable load-displacement curve obtained through numerical simulation gradually approaches a load-displacement curve obtained through the field drawing test by adjusting the slurry binding force (gr _ coh) in unit length in cable unit parameters, so that more accurate rock-soil body-slurry binding strength is obtained; in the first numerical simulation, the initial value of the slurry binding power parameter is the lower limit of the corresponding soil layer ultimate binding strength interval suggested by the relevant specification; if the load-displacement curve obtained by the first numerical simulation is lower than the load-displacement curve obtained by the field drawing test and the maximum value (calculated by adopting a formula (2)) of the difference between the two load-displacement curves with the same load displacement is larger than 5mm, carrying out the second numerical simulation, wherein in the time value simulation, the value of the slurry binding power parameter is increased by 5 percent relative to the initial value; if the load-displacement curve obtained by the first numerical simulation is higher than the load-displacement curve obtained by the field drawing test, and the maximum value (calculated by adopting a formula (2)) of the difference between the two load-displacement curves with the same load displacement is larger than 5mm, carrying out the second numerical simulation, wherein in the time value simulation, the value of the slurry binding power parameter is reduced by 5 percent relative to the initial value; repeating the operation for a plurality of times until the maximum value of the difference between the load-displacement curve obtained by numerical simulation and the same load-displacement curve obtained by field drawing test is not more than 5mm, wherein the obtained slurry binding force parameter is more accurate rock-soil body-slurry binding strength;
in the formula: Δ smaxThe maximum value of the difference between the load-displacement curve obtained by numerical simulation and the same load-displacement curve obtained by field drawing test,
the load on the load-displacement curve obtained for the field pull test is paThe displacement of the movable part when in use,
the load on the load-displacement curve obtained by numerical simulation of FLAC3D is paA displacement in time; m is the number of data points on the load-displacement curve;
(8) carrying out secondary design optimization of the prestressed anchor cable body based on the obtained more accurate rock-soil body-slurry bonding strength; the secondary design optimization aims at minimizing the use amount of the required prestressed anchor cable material by adjusting the length and the position of the anchoring section, the length of the free section, the diameter of a drilled hole and slurry parameters (including slurry materials and grouting pressure) of the prestressed anchor cable on the basis that the ultimate uplift bearing capacity of the prestressed anchor cable meets the bearing capacity required by the prestressed anchor cable, thereby reducing the construction cost to the maximum extent; the adjustment of the design parameters of the prestressed anchor cable is developed based on the formula (3):
in the formula: f is the safety factor, NkThe bearing capacity, R, required to be provided for the prestressed anchor cablekD is the diameter of the anchoring section of the prestressed anchor cable, q is the ultimate uplift bearing capacity of the prestressed anchor cablesiThe bonding strength between the anchoring section of the prestressed anchor cable and the i-th soil layer is liThe length of the anchoring section of the prestressed anchor cable in the ith soil layer is determined;
(9) based on the obtained optimized anchor segment length and position, free segment length, drilling diameter and slurry parameters, developing a FLAC3D simulation prestressed anchor cable pulling test to verify whether the bearing capacity of the prestressed anchor cable meets the requirements; if the requirements are not met, returning to the previous step, and carrying out secondary design optimization again; if the requirements are met, entering the next step;
(10) checking and calculating the integral stability of the anchor-pull type supporting and blocking structure; the overall stability checking calculation of the anchor-pull type retaining structure is carried out by adopting an arc sliding strip division method (formula (4)); if the integral stability of the anchor-pull type retaining structure does not meet the standard requirement, returning to the step (8) and carrying out secondary design optimization again; if the overall stability of the anchor-pull type supporting and blocking structure meets the standard requirement, the next step is continued to be carried out;
min{Ks1,Ks2,…,Ksn}≥Ks (4)
in the formula: k issb(b is 1,2, …, n) is the ratio of the slip moment to the slip moment of the b-th slip arc, KsThe safety coefficient is integrally stabilized for the arc sliding; n is the total number of sliding arcs;
(11) determining the initial tension of the prestressed anchor cable, and carrying out head design of the prestressed anchor cable; the initial tension of the prestressed anchor cable is determined according to the design load of the prestressed anchor cable and the deformation control requirement of the anchor-pulling type retaining structure; the design content of the head of the prestressed anchor cable is to determine the pedestal material, the thickness of the pressure-bearing backing plate, the type of the anchor and the form of the waist rail.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method introduces the FLAC3D numerical simulation into the traditional prestressed anchor Cable design process, and enables the load-displacement curve obtained by numerical simulation in the prestressed anchor Cable pulling process to approach the load-displacement curve obtained by a field pulling test by adjusting the slurry bonding strength parameter of a Cable unit in the FLAC3D, so that more accurate rock-soil body-slurry bonding strength can be obtained, and the defects of over-conservative design and engineering material waste caused by the fact that the lower limit of a reference value interval is taken as the limit bonding strength in the traditional design method are overcome;
(2) the method not only makes full use of the advantages that the FLAC3D can conveniently adjust parameters such as the length of the anchoring section, the hole diameter of the drilled hole, the number and the specification of the steel strands and the like, but also makes full use of the results of the field pulling test of the prestressed anchor cable, can greatly reduce the times of the field pulling test of the prestressed anchor cable, and can carry out parameter analysis based on the more accurate bonding strength between rock and soil mass and slurry of different soil layers obtained by optimization, thereby having important significance for further optimizing the design scheme of the prestressed anchor cable and reducing the construction cost.
Drawings
FIG. 1 is a flow chart of a method for optimizing a prestressed anchor cable design in an anchor-pulling type retaining structure based on FLAC 3D;
FIG. 2 is a schematic view of a prestressed anchor cable load-displacement curve when slurry adhesion parameters are gradually increased;
FIG. 3 is a schematic view of a prestressed anchor cable load-displacement curve when slurry adhesion parameters are gradually reduced;
FIG. 4 is a grid of a FLAC3D simulation prestressed anchorage cable pull test;
FIG. 5 is a schematic diagram of the position of a prestressed anchor cable in the soil layer;
FIG. 6 is a pre-stressed anchor cable load-displacement curve when the rock-soil mass-slurry bonding strength of a sand layer takes different values;
FIG. 7 is a comparison of load-displacement curves before and after optimization of the pre-stressed anchor cable design scheme.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
As shown in fig. 1, it is a flowchart of a method for optimizing a design of a prestressed anchor cable in an anchor-pulling type retaining structure according to the present invention; the design optimization method comprises the following steps: s1, understanding engineering details and carrying out engineering geological investigation to obtain a soil layer histogram and basic physical and mechanical parameters of a rock-soil body; s2, calculating the anchor pulling load required by rock and soil mass and structural object stabilization; s3, determining the arrangement and installation angle of the prestressed anchor cables; s4, calculating the bearing capacity required by the prestressed anchor cable; s5, preliminary design of the prestressed anchor cable; s6, carrying out a prestressed anchor cable field drawing test; s7, combining a prestressed anchor cable field drawing test with a FLAC3D simulation to obtain more accurate rock-soil body-slurry bonding strength (as shown in figures 2 and 3); s8, carrying out secondary design optimization of the pre-stressed anchor cable; s9, simulating a field drawing test by using the FLAC3D to verify the bearing capacity of the prestressed anchor cable; s10, checking and calculating the integral stability of the anchor-pull type supporting structure; and S11, determining the initial tension of the prestressed anchor cable, and designing the head of the prestressed anchor cable.
Example (b):
a design optimization method for a pre-stressed anchor cable in an anchor-pulling underground diaphragm wall of a sandy gravel stratum.
Step 1: understanding engineering details and engineering geological investigation; the engineering is a dry dock foundation pit of a fish beam continent section immersed tube tunnel of east-west axis road engineering in Xianyang city, the excavation depth of the foundation pit is 10.75m, and a foundation pit support structure is an anchoring ground connecting wall; the stratum is divided into a silt layer, a fine sand layer and a pebble layer from top to bottom, and the thicknesses of the silt layer, the fine sand layer and the pebble layer are respectively 3m, 7m and 10 m; the physical and mechanical parameters of the soil layer are shown in table 1.
TABLE 1 soil layer parameters
Step 2: the anchor pulling load meeting the requirements on the stability of rock and soil mass and a structural object is calculated by adopting an elastic fulcrum method to be 453.2 kN;
and step 3: determining the arrangement and installation angle of the prestressed anchor cable; according to the conditions of nearby buildings and the positions of anchoring stratums, the horizontal spacing of the prestressed anchor cables is determined to be 2m, the vertical spacing is determined to be 2.0m, the thickness of a soil layer covering the anchoring section is 5.0m, the soil layer arranged on the anchoring section is a fine sand layer and a pebble layer, the length of the anchoring section in the fine sand layer is 3m, and the length of the anchoring section in the pebble layer is 9m by reference to relevant specifications; the installation angle of the prestressed anchor cable is 25 degrees;
and 4, step 4: calculating to obtain the bearing capacity of 500kN required by the prestressed anchor cable;
and 5: carrying out preliminary design of a prestressed anchor cable; determining the type of the prestressed anchor cable as a tension type, wherein the pulling resistance safety coefficient of an anchoring body of the prestressed anchor cable is 1.4, the tensile safety coefficient of a rib body of the prestressed anchor cable is 1.6, the diameter of the prestressed anchor cable is 0.133m, the cohesive force between mortar and the prestressed anchor cable in a fine sand layer is 18kPa, the comprehensive friction angle of a soil layer is 27 degrees, the cohesive force between the mortar and the prestressed anchor cable in a pebble layer is 200kPa, and the comprehensive friction angle of the soil layer is 42 degrees;
step 6: based on the obtained initial design parameters of the prestressed anchor cables, carrying out 2 groups of prestressed anchor cable field drawing tests;
and 7: a field drawing test is simulated by adopting FLAC 3D; in the FLAC3D numerical simulation, the overall size of a model grid is 20m × 40m × 20m (as shown in fig. 4), and the positions of prestressed anchor cables in the soil layer are shown in fig. 5; simulating a soil layer by adopting an eight-node hexahedron unit, and simulating a prestressed anchor Cable by adopting a Cable unit; the values of the parameters of the Cable unit are shown in Table 2; by adjusting the slurry binding power of the fine sand layer in unit length in the Cable unit parameters, grouting a prestressed anchor Cable load-displacement curve obtained by FLAC3D simulation to approach a prestressed anchor Cable load-displacement curve obtained by a field drawing test (as shown in figure 6), so that more accurate rock-soil body-slurry binding strength of the fine sand layer is 30kPa, and more accurate rock-soil body-slurry binding strength of the pebble layer is 200 kPa;
table 2FLAC3D initial value of Cable unit parameter in simulated prestressed anchor Cable pulling test
And 8: carrying out secondary design optimization of the prestressed anchor cable based on FLAC3D parameter analysis that the ultimate uplift bearing capacity of the prestressed anchor cable meets the bearing capacity required to be provided by the prestressed anchor cable; the anchoring section length of the pre-stressed anchor cable obtained after secondary design optimization is adjusted to 9m (all the pre-stressed anchor cable are positioned in a pebble stratum) from 12m, the diameter of the pre-stressed anchor cable is adjusted to 0.110m from 0.133m, and the installation angle of the pre-stressed anchor cable is still 25 degrees;
and step 9: based on the parameters obtained in the step 8 after the secondary design optimization of the prestressed anchor cable, developing a FLAC3D simulation prestressed anchor cable pulling test, and verifying whether the bearing capacity of the prestressed anchor cable meets the requirements or not; for example, as shown in fig. 7, a pair of an optimized prestressed anchor cable load-displacement curve obtained by FLAC3D simulation and an optimized prestressed anchor cable load-displacement curve before optimization shows that the optimized prestressed anchor cable can provide a limit bearing capacity of 600kN and meet the requirement of 500kN on the bearing capacity of the prestressed anchor cable;
step 10: the integral stability of the anchor-tied ground connecting wall is checked based on the arc sliding strip division method, and the integral stability meets the standard requirement;
step 11: according to the design load (500kN) of the prestressed anchor cable and the deformation control requirement (the maximum displacement of the wall top does not exceed 50mm) of the anchor pulling diaphragm wall, determining that the initial tension of the prestressed anchor cable is 42% of the design load of the prestressed anchor cable, namely 210 kN; and (3) carrying out head design of the prestressed anchor cable, and determining that the pedestal is made of C25 reinforced concrete, the pressure-bearing backing plate is a steel plate, the thickness of the pedestal is 2cm, the type of the anchor is an OVM type 6-hole anchor, and the type of the waist beam is section steel.
The foregoing is only a preferred embodiment of the present invention, and although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (10)
1. A design optimization method of a prestressed anchor cable in an anchor-pull type retaining structure is characterized by comprising the following steps:
s1: the method comprises the following steps of (1) knowing engineering details and carrying out engineering geological investigation to obtain soil layer information and basic physical mechanical parameters;
s2: calculating the anchor pulling load required by meeting the stability of rock and soil mass and structural objects;
s3: determining the arrangement and installation angle of the prestressed anchor cable;
s4: calculating the bearing capacity required to be provided by the prestressed anchor cable;
s5: carrying out preliminary design on a prestressed anchor cable body;
s6: carrying out a prestressed anchor cable field drawing test;
s7: the FLAC3D is adopted to simulate the prestressed anchor cable field drawing test, and the slurry binding power parameter of the cable unit is adjusted to enable the prestressed anchor cable load-displacement curve obtained through numerical simulation to gradually approach the load-displacement curve obtained through the field drawing test, so that more accurate rock-soil body-slurry binding strength is obtained;
s8: carrying out secondary design optimization on the prestressed anchor cable;
s9: the FLAC3D is adopted to simulate a field drawing test, and the bearing capacity of the prestressed anchor cable is verified;
s10: checking and calculating the integral stability of the anchor-pull type retaining structure;
s11: and determining the initial tension of the prestressed anchor cable, and carrying out head design of the prestressed anchor cable.
2. The method as claimed in claim 1, wherein in step S1, the soil information and the basic physical mechanical parameters include: soil layer name, soil layer thickness, compression modulus, Poisson's ratio, bulk modulus, shear modulus, internal friction angle, cohesive force, density.
3. The method as claimed in claim 1, wherein in step S2, the anchor retaining structure is divided into a retaining structure and an anchor structure for analysis; the method for calculating the anchor pulling load adopts a beam simulating method, a soil pressure distribution method or an elastic fulcrum method.
4. The method as claimed in claim 1, wherein in step S3, the arrangement and installation angle of the pre-stressed anchor cable are determined based on the conditions of the nearby building and the location of the anchoring ground; the arrangement of the prestressed anchor cables comprises horizontal intervals and vertical intervals of the prestressed anchor cables, the thickness of a soil layer on the anchoring sections and a soil layer arranged on the anchoring sections.
5. The method as claimed in claim 1, wherein in step S4, the calculation formula of the load bearing capacity required to be provided by the pre-stressed anchor cable is as follows:
in the formula: n is a radical of hydrogenkThe bearing force required for the prestressed anchorage cable, FhS is the horizontal distance of the prestressed anchor cables, b is the required anchor pulling load for stabilizing rock-soil mass and structureaAnd calculating the width for the structure, wherein alpha is the installation angle of the prestressed anchor cable.
6. The method as claimed in claim 1, wherein the step S5 includes the following steps: and determining the type of the prestressed anchor cable, the safety coefficient, the diameter of the anchor cable body and the mechanical properties of the anchoring stratum.
7. The method as claimed in claim 1, wherein the slurry binding parameter is slurry binding force per unit length in step S7; in the first numerical simulation, the initial value of the slurry binding power parameter is the lower limit of the corresponding soil layer ultimate binding strength interval suggested by the relevant specification;
if the load-displacement curve obtained by the first numerical simulation is lower than the load-displacement curve obtained by the field drawing test and the maximum value of the difference between the same load displacement and the displacement is more than 5mm, carrying out the second numerical simulation, wherein in the times value simulation, the value of the slurry binding power parameter is increased by 5 percent relative to the initial value;
if the load-displacement curve obtained by the first numerical simulation is higher than the load-displacement curve obtained by the field drawing test and the maximum value of the difference between the same load displacement and the displacement is more than 5mm, carrying out the second numerical simulation, wherein in the times value simulation, the value of the slurry binding power parameter is reduced by 5 percent relative to the initial value;
and repeating the operation for a plurality of times until the maximum value of the difference between the load-displacement curve obtained by numerical simulation and the same load displacement between the load-displacement curves obtained by field drawing test is not more than 5mm, wherein the obtained unit-length slurry binding power is the unit-length slurry binding power corresponding to the more accurate rock-soil body-slurry binding strength.
8. The method as claimed in claim 1, wherein the secondary design optimization is performed to minimize the required pre-stressed anchor cable material amount by adjusting the anchoring section length and position, the free section length, the bore diameter, and the slurry parameters of the pre-stressed anchor cable based on the ultimate pulling resistance of the pre-stressed anchor cable satisfying the required bearing capacity of the pre-stressed anchor cable in step S8.
9. The method for optimizing the design of the prestressed anchor cables in the anchor-pull type retaining structure according to claim 1, wherein in the step S10, the overall stability of the anchor-pull type retaining structure is checked by using a circular arc sliding strip method.
10. The method as claimed in claim 1, wherein in step S11, the initial tension of the pre-stressed anchor cable is determined according to the design load of the pre-stressed anchor cable and the deformation control requirement of the anchor-pulling type retaining structure; the design content of the head of the prestressed anchor cable is to determine a pedestal material, the thickness of a pressure-bearing base plate, the type of an anchorage device and the form of a waist beam.
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