宜巴高速岩堆不同密实度大型直剪强度特性

STREBGTH BEHAVIOR OF ROCK DEBRIS HEAPS WITH DIFFERENT DENSITIES IN YIBA EXPRESSWAY

岩堆是指陡峻山坡上,岩体崩坍物质经重力搬运,在山坡坡脚或平缓山坡上堆积的松散堆积体。拟建的宜巴高速公路线路方案穿越多处大型岩堆体,且地质条件复杂,各处岩堆体的密实程度各不相同。不同密实程度的岩堆体的强度和稳定性差异很大,对项目建设造成极大不利。为此进行了相同含水量不同密实度的岩堆体大型直剪强度特性实验,结果表明:岩堆体含水量、密度均存在很大的不均匀性,岩堆充填和胶结物含水量5%～7%,平均含水量为6.5%,干密度最大值2.246g.cm-3,平均天然密度为2.112g.cm-3,平均干密度1.982g.cm-3;除干密度2.10g.cm-3试样在低垂直压力(50,100,200kPa)下分别出现剪切力峰值116.04,154.7,210.82kPa以外,其余各垂直压力下剪切力随水平剪切位移增大而增加,没有明显峰值,表现出明显的应变硬化特征;岩堆体直剪强度指标c和φ随着其干密度的增加而增加,相同含水量下一般岩堆体越密实,其抗剪强度越高;原始级配不同干密度下,随着岩堆体密实度增加,其抗剪强度对密实度的敏感性大幅度下降。

Heap（ or talus） refers to the accumulation of loose material lies in hillside toe or gentle slope that rock materials are handled by gravity. The proposed appropriate highway route schemes through many large broken rock debris stockpiles （ or heaps）. The geological conditions are complicated. The compaction degrees of rock piled mases everywhere are also not identical. The strength and stability of different compction degrees of rock debris piled masses are different greatly. They have huge disadvantages to the project construction. For this reason, experiments of large direct shear strength characteristics of rock debris piled masses with same water content and different densi- ties are carried out. The result shows the follows. The evenness of heap mass moisture contents and densities are very poor. The rock heap filling and cementing content moisture are about 5% -7%. The average water content is 6.5%. The maximum of dry density is 2. 25 g.cm-3. The average of natural density is 2. 11 g.cm-3. The average ofdry density is 1.98 g. cm-3. The samples in low vertical pressure（50, 100, 200kPa） appear the shear stress peaks 116, 154 and 211 kPa respectively when the dry density is 2. 10 g. cm-3. The other results show that the shear stress increases with the shear displacement, has no clear peak, and displays strain hardening characteristics obviously. The parameters of rock mass＇ direct shear strength （ c and ） increase with the dried density. The general rock heap mass with the same water content is more reinforced when the shear strength is higher. The sensitivity of shear strength to compactness falls drastically with the increase of rock heap mass density in the original gradation and different dry densities.