{"id":5959,"date":"2013-02-14T08:57:13","date_gmt":"2013-02-14T08:57:13","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=5959"},"modified":"2013-02-14T09:00:22","modified_gmt":"2013-02-14T09:00:22","slug":"the-geology-and-a-possible-mechanism-of-the-hatfield-stainforth-colliery-landslide","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2013\/02\/14\/the-geology-and-a-possible-mechanism-of-the-hatfield-stainforth-colliery-landslide\/","title":{"rendered":"The geology and a possible mechanism of the Hatfield Stainforth colliery landslide"},"content":{"rendered":"

Unfortunately, overnight no new images have appeared of the Hatfield Stainforth landslide<\/a>, so it is difficult to know whether the landslide has now stopped moving.\u00a0 The morphology of the landslide<\/a> continues to suggest to me that this is a bearing capacity failure.\u00a0 I have taken a quick look at the excellent BGS Geology of Britain Viewer<\/a>, which produces the following map (I have marked the approximate location of the colliery at which the landslide at occurred):<\/p>\n

\"\"<\/a>

copyright BGS: http:\/\/mapapps.bgs.ac.uk\/geologyofbritain\/home.html<\/p><\/div>\n

The map shows that underlying the location of the spoil tip is a layer of alluvium – basically soft sediments such as sands and gravels deposited by ancient rivers.\u00a0 These are comparatively weak materials, especially when wet.\u00a0 So, my hypothesis is that the weight of the spoil tip has caused the development of a failure through these materials, which has then generated a landslide with a rotational geometry.\u00a0 The sketch below is my suggested interpretation, with the spoil sitting over a layer of alluvium.\u00a0 The very wet weather over the last few months has led to a high groundwater level, which in turn has reduced the strength of the alluvium.\u00a0 This has then failed with the geometry shown in the upper sketch – the rotational landslide has then progressively moved to generate the geometry in the bottom sketch:<\/p>\n

\"\"<\/a><\/p>\n

The good news is that this type of landslide is self-stabilising – eventually there is enough material uplifted to balance the load of the spoil, and movement terminates.\u00a0 However, from this it is not difficult to understand from this why it is a challenge to re-establish the railway line.\u00a0 If the uplifted material under the tracks is removed the spoil will not be in balance and the landslide will reactivate.\u00a0 So, to stabilise this slide either the spoil at the back of the displaced block will need to be removed or the strength along the shear surface will need to be increased.\u00a0 Neither are straightforward.\u00a0 Only when that is achieved can the material under the track bed be excavated.<\/p>\n

Incidentally, back at the end of November I noted the following in relation to landslides in the UK<\/a>:<\/p>\n

So what next?<\/strong><\/p>\n

The heavy rainfall has now moved away, to be replaced by cold weather, so the immediate threat should start to subside.\u00a0 However, for some slopes the groundwater level will still be rising as the rainfall percolates through, so more landslides are possible.\u00a0 It is notable though that all of the above landslides are shallow \u2013 so far there is not much sign of the deep-seated landslide systems reactivating.\u00a0 This is almost certainly because groundwater levels were so low after the prolonged drought that ended in the early summer.\u00a0 These deep groundwater levels will now be rising, so don\u2019t be at all surprised if there are reports of larger landslide movements over the next few months.\u00a0 Places such as Dorset and the Isle of Wight, where there are large coastal landslide systems, will be particularly vulnerable.\u00a0 Such landslides represent a comparatively low level of risk to life, but can cause extensive property damage.\u00a0 It will be an interesting winter.<\/p><\/blockquote>\n

Thus, it is not really surprising that we are now seeing deep-seated landslides developing.\u00a0 I expect that there will be more over the next two or three months.<\/p>\n","protected":false},"excerpt":{"rendered":"

The geology map of the Hatfield Stainforth landslide site shows the site is underlain by alluvium. This suggests a bearing capacity failure<\/p>\n","protected":false},"author":22,"featured_media":5962,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[698,233,695,469,959,697,133],"class_list":["post-5959","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-landslide-report","tag-bearing-capacity","tag-coal-mine","tag-colliery","tag-featured","tag-landslide-report","tag-rotational-failure","tag-uk"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/5959","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/comments?post=5959"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/5959\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/5962"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=5959"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=5959"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=5959"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}