巖質(zhì)邊坡穩(wěn)定分析 (1)課件

1、滑坡復(fù)活滑坡復(fù)活從力學(xué)特性來看分為五類1、巖石崩塌2、平移滑動3、旋轉(zhuǎn)滑移4、巖塊流動5、巖層曲折邊坡邊坡變形和破壞變形和破壞地質(zhì) Rockslide at Yosemite National Park, California kills one, injures 47. 不穩(wěn)定邊坡的防治措施不穩(wěn)定邊坡的防治措施平整坡面以免坑洼地積水平整坡面以免坑洼地積水外圍挖溝槽以阻斷地表水流向坡體外圍挖溝槽以阻斷地表水流向坡體坡體上修筑排水溝坡體上修筑排水溝防地表防地表水入滲水入滲Surface Drainage on a slope on the road into Runswick Bay, a co

2、astal 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-horizontal boreholes under a tip of urban refuse which was sliding downhil

3、l 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 variety of ways to stabilize slopes. Gros Ventre Landslide Wyoming Traits:l

4、argest 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 from Grand Teton mountains across valley to E to Gros Ventre Range and

5、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 from interior of hummocky toe to other side of valley where Tensleep s

6、andstone 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. It is commonly seen as curved tree trunks as in the above phote. Imp

7、ortant 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 exposed soil and rock, marks the top of a landslide. The toe is the

8、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 Motivation A Most landslides (or potential slides) can be recognized or predi

9、cted 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 cost of the desired facility; they should be avoided.III Signs of pa

10、st 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/pic13_2.html a Oblique aerial photos: Figs. 2.19, 2,22, 2.23, 2.28, 2.33

11、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 (seasonal photos useful) a Oblique aerial photos: Plate 3.3 a Stereophot

12、os: 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 3 Phreatophytes and seeps 4 Patched or hummocky roads 5 Tilted walls

13、, 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. Individual soil or rock particles are raised at right angles to the slop

14、e 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. Jipazi