岩质边坡稳定分析 ()PPT课件

1、复活复活表表6 61 1 我国我国8080年代重大崩、滑灾害事件年代重大崩、滑灾害事件从力学特性来看分为五类1、岩石崩塌2、平移滑动3、旋转滑移4、岩块流动5、岩层曲折边坡边坡变形和破坏变形和破坏地质 湖北秭归县沙镇溪千将坪特大滑坡全貌湖北秭归县沙镇溪千将坪特大滑坡全貌Rockslide at Yosemite National Park, California kills one, injures 47. 不稳定边坡的防治措施不稳定边坡的防治措施平整坡面以免坑洼地积水平整坡面以免坑洼地积水外围挖沟槽以阻断地表水流向坡体外围挖沟槽以阻断地表水流向坡体坡体上修筑排水沟坡体上修筑排水沟防地表防地表

2、水入渗水入渗Surface Drainage on a slope on the road into Runswick Bay, a coastal village in Yorkshire, EnglandIn the Henllys landslide in South Wales trench drains have been dug in front of the landslip, so that it will slide over the top, and be drained from underneath. Drains are installed in near-horiz

3、ontal boreholes under a tip of urban refuse which was sliding downhill near Ancona, Italy. This diagram shows a coastal landslide with several systems of drainage Drains are installed in near-horizontal boreholes from shafts in a coastal landslide at Herne Bay, Kent. Drains are installed in a variet

4、y of ways to stabilize slopes. Gros Ventre Landslide Wyoming Traits:largest historic slide in U. S. June 23rd, 1925. 40 million metric tons. followed heavy rains and snow melt. formed 40-60 meter deep lake. beds dipping parallel to slope. ranch destroyed by rising lake. 1927 break out flood. View fr

5、om Grand Teton mountains across valley to E to Gros Ventre Range and large flake scar on mountain side.Upper part of slide showing where basal slip surface at bottom of Tensleep sandstone (on top of Amsden Formation clay beds) is exposed. Note intact sliver with trees half way down bare scarp.View f

6、rom interior of hummocky toe to other side of valley where Tensleep sandstone rode up and against in place Chugwater red clastics.View from head scarp scar with snow to translational slide block in middle to hummocky toe at base.Creep is the unnoticed slow movement of unconsolidated soils downslope.

7、 It is commonly seen as curved tree trunks as in the above phote. Important to look for when buying real estate but not life-threatening. An earth flow near Interstate Highway 70, Ellsworth County. The head is the upslope portion of the landslide. The scarp, the steeply inclined failure surface with

8、 exposed soil and rock, marks the top of a landslide. The toe is the downslope portion of the landslide. A mound of soil called a lobe marks the toe of the landslide. RECOGNITION OF AREAS OF POTENTIAL SLOPE FAILURE (25)I Main Topics A Motivation B Signs of slope instability http:/anaheim- I Motivati

9、on A Most landslides (or potential slides) can be recognized or predicted if the proper investigations are performed in advance. B Except for small slides, slides typically cost far less to prevent than to fix (An ounce of revention is worth a pond of cure.). C Massive slides may cost many times the

10、 cost of the desired facility; they should be avoided.III Signs of past slope instability (focus on topography and hydrology) A Review of maps (Figs. 4.5, 3.9 in SR 176) B Review of aerial photos & remote sensing imagery in SR 176 1 Hummocky topography /Publications/pic13/pic1

11、3_2.html a Oblique aerial photos: Figs. 2.19, 2,22, 2.23, 2.28, 2.33 b Stereophotos: Figs. 3.14, 3.26, 3.31 2 Arcuate fractures and old scarps or scars http:/anaheim- a Oblique aerial photos: Figs. 2.19, 3.40, b Stereophotos: Figs. 3.5, 3.7, 3.14, 3.19, 3.20, 3.24 3 Areas of anomalous vegetation (se

12、asonal photos useful) a Oblique aerial photos: Plate 3.3 a Stereophotos: Plates 3.1, 3.2 4 Areas of seepage: Vertical infrared imagery: Fig. 3.35 5 Sand flows and talus (Figs. 3.25, 3.30 ) C Features to examine in field reconnaissance 1 Ground cracks (Fig 4.2 in SR 176) 2 Closed hillside depressions

13、 3 Phreatophytes and seeps 4 Patched or hummocky roads 5 Tilted walls, trees, and fencesSurface signs of soil creep. Leaning power and telephone pole, fences and gravestones, and trees bending first downslope before growing straight up may provide evide of soil creep.The mechanics of soil creep. Ind

14、ividual soil or rock particles are raised at right angles to the slope by swelling or expansion and then settle vertically downward during compaction or contraction. The net result is slow downslope creep.EARTHFLOW : Soil and other surface materials move downslope as a viscous flow.SLUMP : a type of rotational slide.BLOCK SLIDE : The sliding mass is moving along a planar surface. Jipa