It is shown that the vertical cracks will appear at both sides of the fill, and the critical depth of the cracks, which do not change with the fill width, is approximately equal to the magnitude obtained by the Rankine theory. The comparison between the theoretical and the numerical results demonstrate the rationality of the proposed theory. The formulae of the resultant force coefficient and the distribution of the active earth pressures on the retaining wall are put forward. Based on the numerical analysis results, a new theoretical model is presented considering the adhesion between the wall and the fill as well as the vertical cracks in the fill.
The critical depth of the vertical cracks and the slip surfaces in the backfill are discussed.
#Soil nail flac3d software
The software ABAQUS is used to execute the numerical simulation of active earth pressures on the rigid retaining wall with narrow cohesive backfill. So it is not appropriate to use the Coulomb or Rankine theory to calculate the active earth pressures on the retaining wall. In the case of a retaining wall adjacent to an existing basement or a vertical rock face, the width of backfill is limited. YING Hong-wei, ZHU Wei, HUANG Dong, XIE Xin-yu, LI Bing-he
The rule that the secondary grouting should be made after body strength achieves 5 MPa is hard to execute, so we suggest to make it during the period from the initial setting to the final setting.Īctive earth pressures against rigid retaining walls with narrow cohesive backfill The design service life of temporary anchors should be increased to 5 years from 2 years to better meet the needs of engineering now.
#Soil nail flac3d free
The free length of the anchor needs not be strictly limited, and it should be 4~6 m so as to better control the deformation of support system. The timing method for the creep rate formula should be clear in the creep tests, otherwise the creep rate index would be meaningless. The expanding detection numbers are suggested to 2 times the unqualified anchor numbers in acceptance tests. In basic tests, the stable index 0.1 mm is a clerical error during the stability load period, it should be 1.0 mm the anchor length should not be cut short since the shorter anchor gets the too high bonding strength the maximum test load should be collapse load for the limit bond strength. There exist serious defects in soil anchor level rigidity coefficient formula, and meaning of the formulas is not clear, so we suggest to modify and improve it. There are some controversies on some rules for the prestressed anchors in some technical standards. The pile internal forces of PSN decreases with the increase of the length of soil nails.ĭiscussion of some rules for prestressed anchors in some technical standards
When the ratio of the nail length to the excavation depth (L/H) is 0.33, the soil-arching effect is very obvious, and the sliding surface morphology of PSN is similar to that of scattered pile retaining structure, However, when the L/H ratio is 0.67, the soil-arching effect is not obvious, and the sliding surface morphology of PSN is similar to that soil-nailing retaining structure. The length of soil nails has significant effects on the stability, failure mode and soil-arching effect of PSN. The results of five groups of tests performed on the centrifuge in Tongji University show that the soil nailing of PSN can greatly increase the stability of cuttings. Home About Journal Editorial Board Fund Council Editorial Call for Contributions and Subscription Micro-journal Contact Us Message ChineseĬentrifuge tests on soil-nailing reinforcing effect in scattered row piles and soil nailing for excavationsĪ centrifuge study on pile-soil nailing (PSN) is carried out by Tongji University. Chinese Journal of Geotechnical Engineering 岩土工程学报
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