膨胀岩工程特性试验研究

为研究南水北调中线工程膨胀岩的工程特性,选取新乡潞王坟段的代表性岩层——强风化黏土岩和泥灰岩的原状样及扰动样,进行了物理性质试验、击实试验、力学性质试验以及膨胀特性试验。试验成果表明:对扰动样的标准击实基本上很难达到天然状态下的干密度状态,土体的结构性在击实过程中不能得到较好的恢复;初始含水率越小,吸湿能力越大,其强度降低程度越大,饱和强度参数越小;含水率低的试样,其破坏强度大,但破坏应变小;相同的压实度下,含水率越低试样的软化现象越明显;相同压实度的土样,含水率越大,其初始切线模量越小;压实度在90%~98%,压实度越大,膨胀力与膨胀率越大;随着压实度超过98%,膨胀率与压实度关系曲线存在一峰值转折点,而且此峰值点出现在压实度为98%~100%。压力与膨胀率关系曲线分两直线段:一陡降段和一平缓段,各曲线之间近似平行,曲线截距为无荷膨胀率数值。该成果为南水北调中线工程膨胀岩渠坡段的设计施工提供了科学依据。

Experimentation study on engineering property of swelling rocks

The representative strong rotten claystone and marlstone rock samples with undisturbed and disturbed state are selected at the Xinxiang Luwangfen test zone in middle-route of South-North water transfer project.Through a series of soil mechanics experimentation the physical,mechanical and swelling properties of swelling rock has been well studied.The result shows that density of disturbed samples under standard compaction test would be very difficult to reach the dry density in natural state,because the structure of rock can not be restored in this compaction process.The less initial water content is,the larger competence of absorbing water becomes and the larger strength reduction degree is,also the smaller saturation strength parameter is.When the water content of sample is low,its strength is big but the failure strain is small.In the same compaction degree the lower water content is,the more obvious strain softening phenomenon is.In the same compaction degree the larger water content is,the smaller initial tangent module is.When the compaction degree is from 90% to 98%,the larger compaction degree becomes,the lager expansion pressure and expansion rate are.But when the compassion degree exceeds 98%,there is one peak milestone in the relation curve between expansion rate with compaction degree,and this milestone exists in the range of 98% to 100%.The relation curve between pressure and expansion rate can be divided into two line parts,one is steep drop seagment and the other is gentle seagment,and each curve is in parallel approximately,and the intercept of that curve is the expansion rate under no-load state.The result can supply scientific reference for the design and construction of swelling rock slope in middle-route of South-North water transfer project.