Evaluation and Mitigation of Membrane Compliance Effects in Soil Liquefaction Testing

液化是一种潜在的破坏性地面破坏类型，通常与细粒土壤有关。然而，有证据表明，在以下地震中，粗粒土如砾石中发生了液化：日本福井(1948年)；阿拉斯加(1964年)；唐山(1976年)，中国；博拉(1984)，爱达荷州。尽管有这些证据，但在实验室测试中从未观察到砾石土中的液化。据推测，这在某种程度上是由于实验室测试未能重现砾石土的就地性能。这种失败的最有可能的原因是“膜顺应性效应”。当在实验室测试中机械加载时，土壤样品必须保持在顺应性橡胶膜中。由于其顺应性，膜能够穿透到颗粒之间的表面空隙中，并且这种穿透随着土壤颗粒的粗糙度而增加。这项研究计划的目标是开发改进的实验室测试程序，以消除液化测试中的这种膜顺应性影响。私家侦探是一名年轻的调查员，有着出色的记录。他有可用的设施来完成拟议的研究。砾石液化对各种大型建筑工程具有严重的经济后果，因为必须对补救工作的必要性做出决定：在设计和施工这些工程时，没有认识到砾石土的液化潜力。建议批准此支持请求。

Liquefaction, a potentially destructive type of ground failure, is commonly associated with fine-grained soils. Yet evidence exists that liquefaction occurred in coarse-grained soils such as gravels in the following earthquakes: Fukui (1948), Japan; Alaska (1964); Tangshan (1976), China; Mt. Borah (1984), Idaho. In spite of this evidence, liquefaction in gravelly soils has never been observed in laboratory tests. Presumably, this is due in some way to the failure of laboratory tests to reproduce the in-situ performance of gravelly soils. The most probable reason for this failure is the "membrane compliance effect." Soil samples must be held within a compliant rubber membrane when loaded mechanically in laboratory tests. Due to its compliance, the membrane is able to penetrate into the surface voids between grains, and this penetration increases with the coarseness of the soil particles. The objective of this research program is to develop improved laboratory testing procedures to eliminate this membrane compliance effect in liquefaction testing. The P.I. is a young investigator with an outstanding track record. He has the facilities available to accomplish the research proposed. The liquefaction of gravels is of serious economic consequence for various large construction projects because decisions have to be made as to the necessity of remedial work: the liquefaction potential of gravelly soils was not recognized when these projects were designed and constructed. It is recommended that this request for support be approved.