郭家镇隧道泥岩膨胀特性试验研究

Experimental Study on the Expansion Characteristics of Mudstone in Guojiazhen Tunnel

宝鸡至兰州客运专线7标郭家镇隧道穿越第三系泥岩、砂质泥岩地层,该套地层岩体含有较多的亲水矿物,具有遇水膨胀、软化、失水崩解、开裂的典型膨胀性特征,在隧道施工前,需要掌握泥岩膨胀特性,以对隧道施工方法、支护结构进行合理设计。以隧道穿越的泥岩为研究对象,采用室内试验为手段,对泥岩膨胀性进行了研究。具体工作内容包括:现场采集大块岩样;室内加工岩样,得到了满足试验要求的原始试样;自由膨胀率、侧限膨胀率和膨胀力试验;判定膨胀岩的膨胀特性。研究结论:岩石膨胀力为10.30~95.61 k Pa,径向和轴向自由膨胀率分别0.8%~1.0%和4.8%~6.8%,因此,郭家镇地区灰质泥岩属于弱膨胀性软岩;由最大膨胀力判断出隧道膨胀岩属于弱膨胀岩。试验所得成果可为类似工程地质条件下工程建设提供参考与借鉴。

Guajiazhen Tunnel,the seventh contract section in Baoji-Lanzhou high-speed railway,passes through the rock consisting of tertiary mudstone and sandy mudstone. Many hydrophilic minerals are contained in the rock mass,so the rock is characterized by water swelling,softening,water loss-inducing disintegration and cracking. Therefore,for the purpose of reasonable design of construction method and support structure,expansion characteristics of mudstone should be fully explored. The concrete work includes as follows： to collect the large rock samples in the field; to obtain the test samples which satisfy the experimental requirements by indoor processing; to test free expansion rate,lateral expansion rate and expansion force and to assess the expansion characteristics. Some conclusions drawn from the experiment were： the expansion force is about 10. 30 ~ 95. 61 k Pa and the radial free expansion rate is about 0. 8% ~ 1. 0% with and axial free expansion rate about 4. 8% ~ 6. 8%,so the experimental results indicate that the lime mudstone in Gujiazhen area is classified as weak expansive soft rock,and the expansive rock in Gujiazhen tunnel is weak expansive rock. The test results presented can be referred to in the similar projects under the similar geotechnical condition in future.