初始含水率对饱水泥质粉砂岩性质的影响
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摘要
近年来,川东红层地区多次出现"旱涝急转"的特殊天气,岩体迅速从干旱转为饱水状态,使得物理力学性质产生显著变化,从而导致地质灾害的发生。为了应对这种极端天气,探究初始含水率对岩体饱水浸泡物理力学性质的影响,选取具有代表性的四川中江红层泥质粉砂岩为研究对象,采用烘箱以控制岩样达到不同的初始含水率,在此基础上作饱水浸泡处理。通过控制不同的初始含水率及其烘干温度,研究其对川东红层泥质粉砂岩饱水浸泡的单轴抗压强度及弹性纵波波速的影响,分析并揭示其宏观力学性质和细微观结构的变化规律及原因。试验结果表明:①随着初始含水率的下降,泥质粉砂岩饱水浸泡后单轴抗压强度先小幅增加后大幅降低;弹性纵波波速先缓慢下降后迅速下降。强度的最大值和波速的转折点对应相同的初始含水率。②相同初始含水率下,随着烘干温度的升高,泥质粉砂岩饱水浸泡后强度和波速均呈下降趋势。同时,相比低烘干温度,高烘干温度条件下达到强度最大值与波速转折点所对应的初始含水率降低,强度最大值也降低。
In recent years, the special weather of "a Sharp Turn from Drought to Flood" has appeared many times in the red-bed area of eastern Sichuan. The rock and soil quickly changed from drought to saturated state, which caused significant changes in physical and mechanical properties, thus promoting the occurrence of geological disasters. In order to cope with this extreme weather and study the influence of initial moisture content on the physical and mechanical properties of saturated rock mass, we selected the representative argillaceous siltstone of red layer in Sichuan Zhongjiang as the research object. The rock samples with different initial water content were prepared with oven. By controlling different initial water contents and drying temperatures, the uniaxial compressive strength and elastic longitudinal wave velocity of saturated argillaceous siltstone were studied, and the change laws and causes of the macro and micro mechanical characteristics were revealed. The test results showed that:(1) with the decrease of initial water content, the uniaxial compressive strength slightly increases first and then decreases greatly, and the elastic longitudinal wave velocity decreases slowly and then rapidly. The maximum value of the intensity and the turning point of the wave velocity correspond to the same initial moisture content.(2) The strength and wave velocity of argillaceous siltstone decrease with the increase of drying temperature at the same initial moisture content. At the same time, compared with low drying temperature, the mentioned initial moisture content that corresponds to the peak strength and the turning point of wave velocity decreased under high drying temperature, and the maximum strength also decrease.
In recent years, the special weather of "a Sharp Turn from Drought to Flood" has appeared many times in the red-bed area of eastern Sichuan. The rock and soil quickly changed from drought to saturated state, which caused significant changes in physical and mechanical properties, thus promoting the occurrence of geological disasters. In order to cope with this extreme weather and study the influence of initial moisture content on the physical and mechanical properties of saturated rock mass, we selected the representative argillaceous siltstone of red layer in Sichuan Zhongjiang as the research object. The rock samples with different initial water content were prepared with oven. By controlling different initial water contents and drying temperatures, the uniaxial compressive strength and elastic longitudinal wave velocity of saturated argillaceous siltstone were studied, and the change laws and causes of the macro and micro mechanical characteristics were revealed. The test results showed that:(1) with the decrease of initial water content, the uniaxial compressive strength slightly increases first and then decreases greatly, and the elastic longitudinal wave velocity decreases slowly and then rapidly. The maximum value of the intensity and the turning point of the wave velocity correspond to the same initial moisture content.(2) The strength and wave velocity of argillaceous siltstone decrease with the increase of drying temperature at the same initial moisture content. At the same time, compared with low drying temperature, the mentioned initial moisture content that corresponds to the peak strength and the turning point of wave velocity decreased under high drying temperature, and the maximum strength also decrease.
引文
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[2] Mitchell J K,Soga K,Mitchell J K,et al.Fundamentals of soil behavior[M].Wiley,1976:827-866.
[3] 徐丹,唐朝生,冷挺,等.干湿循环对非饱和膨胀土抗剪强度影响的试验研究[J].地学前缘,2018(1):286-296.
[4] 周翠英,谭祥韶,邓毅梅,等.特殊软岩软化的微观机制研究[J].岩石力学与工程学报,2005,24(3):34-40.
[5] 王森.红层地区软弱夹层形成演化规律及泥化特征研究[D].成都:成都理工大学,2017.
[6] 李江,许强,胡泽铭,等.川东红层原状滑带土饱水软化试验研究[J].岩石力学与工程学报,2015(s2):4333-4342.
[7] 郭永春.红层岩土中水的物理化学效应及其工程应用研究[D].成都:西南交通大学,2007.
[8] 周翠英,谭祥韶,邓毅梅,等.特殊软岩软化的微观机制研究[J].岩石力学与工程学报,2005,24(3):34-40.
[9] Sharma K,Kiyota T,Kyokawa H.Effect of slaking on direct shear behaviour of crushed mudstones[J].Soils & Foundations,2017,25(2):288-300.
[10] 谈云志,胡莫珍,周玮韬,等.荷载-干湿循环共同作用下泥岩的压缩特性[J].岩土力学,2016,37(8):2165-2171.
[11] 陈思娇.四川中江垮梁子滑坡滑带土强度特性及滑坡变形机理研究[D].成都:成都理工大学,2014.
[12] 翟国军.中江冯店垮梁子滑坡基本特征与变形机理研究[D].成都理工大学,2011.
[13] 束骞.环剪试验条件下近水平岩层滑坡滑带土的力学行为特性试验研究[D].成都:成都理工大学,2015.
[14] 姜洪涛,唐朝生,吴静红,等.不同地面覆盖层下土体温湿度场长期观测数据分析[J].工程地质学报,2013,21(6):842-848.
[15] 唐朝生,施斌,崔玉军.土体干缩裂隙的形成发育过程及机理[J].岩土工程学报,2018,40(8):1415-1423.
[16] 姚远.利用CT扫描研究干湿循环泥岩软化过程[J].工程勘察,2014,42(6):12-15.
[17] Panabokke C R,Quirk J P.Effect of Initial Water Content on Stability of Soil Aggregates in Water[J].Soil Science,1957,83(3):185-196.
[18] 邓华锋,李建林,邓成进,等.岩石力学试验中试样选择和抗压强度预测方法研究[J].岩土力学,2011(11):3399-3403.