软硬相间层状复杂岩体综合变形模量原位试验研究

IN-SITU TESTING OF INTEGRATED DEFORMATION MODULUS FOR COMPLICATED ROCK MASS OF SOFT AND HARD INTERLAYERS

某拟建大型电站坝基岩体为一套河湖相沉积岩,包含了砾岩、砂岩、粉砂岩和泥岩等多种岩性岩体。不同岩体变形参数各异,常规变形试验只能获得单一岩性岩体的变形模量,而这种软硬相间层状复杂岩体的综合变形模量是与单一岩性岩体变形模量、岩层倾角、岩层厚度多个因素相关的,如何通过试验获得这种复杂组合岩体的综合变形模量是一个重要问题。本文首先对坝址区不同岩性所占的比例进行了详细的统计,获得砂岩、粉砂岩和泥岩的厚度比为6：2.5：1.5,根据这一统计结果在坝轴线附近选择含有砂岩、粉砂岩和泥岩三种岩体的大型变形试验区,将承压板尺寸设定为200cm×37cm,承压板就能同时覆盖砂岩、粉砂岩和泥岩三种岩体,且将其厚度比确定为6：2.5：1.5。通过在承压板上施加大荷载（250余吨）将应力传至下部多层岩体,从而获得软硬相间层状复杂岩体的综合变形模量。试验结果表明坝基弱下风化岩体的综合变形模量可达到7.0GPa,已经满足筑坝的要求。通过原位试验成功地论证了坝基岩体综合变形模量量值的问题。

The bedrocks for a proposed large power station contain a set of river and lake facies sedimentary rocks.The rocks contain conglomerate,sandstone,siltstone and mudstone and have a variety of lithologies.Different rocks have different mass deformation parameters.Conventional deformation test can only get a single lithology of rock mass deformation modulus.The soft and hard inter-layered rock mass has an integrated deformation modulus that is a function of the single rock mass deformation moduli,the rock bidding angles,and the rock layer thicknesss.How to assess the integrated deformation modulus is an important task.At first,the paper conducts a statistic analysis on the proportion of different lithologies at dam site and obtains that the thickness ratio of the sandstone,siltstone and mudstone are 6：2.5：1.5.According to the statistics,the test area containing sandstone,siltstone and mudstone along the dam axial is selected.The bearing plate size is defined to be 200 cm in length and 37 cm in width for the in-situ test.At the same time,the bearing plate can cover the sandstone,siltstone and mudstone.The plate can transfer the maximum applied load of 250 tons onto the underlain multi-layered rocks.As a result,the integrated deformation of the bedrock can be determined.The experimental results show that for the weak weathered bedrock at the rock dam foundation,its integrated deformation modulus can be up to 7.0 GPa.This value meets the design requirements.