A Study On Geostress Field Characteristics In Area Of Long-tunnel Through Mountain Along Shijiazhuang-Taiyuan Passenger Railway Line

The stress existed naturally in Earth rocks and soil is called geostress, which is a three-dimensional state that formed geostress field. The geostress field research, has the vital significance to the project practice. Before underground engineering designed, particularly deep long-tunnel projects, the date of geostress is need to be measured commonly, and grasps the geostress field characteristics in the area of construction. Two long-tunnels of Shijiazhuang-Taiyuan passenger railway line are located in two physiognomy units of the denudation low mountainous area of south central of the Taihang mountain and the Shanxi loess plateau. The total topography characteristic along the route is that the west is higher than the east and is the mid-west highest of an anisomerous triangle.Through a systematic study on geostress field characteristics in area of long-tunnel through mountain, separately obtains the horizontal stress numerical value and direction of the maximum principal horizontal stress of two tunnel areas. The date was measured from nearby the tunnel's axes in 04-Zd-984 bore in area of Nanliang tunnel that was that the maximal and minimal horizontal stress numerical value were probably 6Mpa and 4Mpa. The dates were measured from nearby the tunnel's axes in 04-Zd-1004 and 04-Z'd-1010 bores in area of Nanliang tunnel that were that both of the maximal horizontal stress numerical value were 21Mpa and 15Mpa probably, and both of the minimal horizontal stress numerical value were 11Mpa and 9Mpa probably, in addition the vertical maximum principal stress may be were 10Mpa and 9Mpa. The order of the three direction of the maximum principal stress was σ_H >σ_h >σ_v, so the area was affected by thehorizontal constructed movement before. And obtains nearby stress numerical value along with the depth distributed rule. Geostress numerical value and direction which got from three bores in Nanliang and Taihangshan mountain long-tunnels, roughly consisted with the neighboring local former geostress material and as well as the regional geology structure characteristics, and explained this local geostress field basic characteristics and the current regional geology structure characteristics in tunnel area. Through researched the geostress characteristics, would advice tunnel project for appropriate hole room shape design, the direction and construction method of the tunnels and so on. And also would provide more bases for the disaster forecast and the renovation of the tunnels.