In the urban area, the city function concentrates on it, so a great many subway and basement parking lot etc. is built to make good use of area. And so the excavation work has a large scale and a high depth. Then today's the artesian head in the urban area has risen suddenly. As a result, the excavation work becomes important to check the stability for heaving when an earth retaining wall is executed in ground with high artesian head. Here, the excavation work of ‘the HIGASHI-KAWAGUCHI STATION of SAITAMA EXPRESS RAILWAY’ adopted the new countermeasure using 230 piles for heaving.
This report describes the design, the actual construction of the new countermeasure for heaving and result of various measurements during excavation.

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　荒川が決壊し大規模な水害が発生した場合における地下鉄等の浸水状況を把握するために，氾濫域にある地下鉄等の出入口及びトンネルにおける止水板，防水扉等の止水施設の設置状況や乗換駅における各路線の接続状況等を把握して浸水シミュレーションモデルを構築し，地上部と地下鉄等の浸水状況の把握を行った．その結果，地下鉄等のトンネルや乗換駅等を通じて地下空間が広範囲に浸水すること，東京駅等において地上部よりも早く地下鉄等のトンネルを通じて氾濫水が到達する場合があること，足立区千住地先で決壊した場合，地上の浸水範囲は局所的であるにもかかわらず都心部を含む広い範囲が水没状態になること，出入口等に応急的な止水対策等を行うことで，浸水区間の減少や浸水開始時間の遅延に対して効果を発揮する場合があることなどが分かった．

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 This study verifies the vulnerability of Tokyo to natural disasters. Landforms distributed in Tokyo are classified into Yamanote upland, Tokyo lowland, Tamagawa lowland and coastal lowland. Among these, the Tokyo lowland has suffered from natural disasters several times because its elevation is low and thick soft soil covers a broad area. River courses of the Tone and Ara Rivers flowing through the Kanto lowland to Tokyo Bay were modified for shipping and for agriculture on the flood plains in the 17^th century. Withdrawal of ground water due to industrial use from the end of the 19^th century to the beginning of 1970's caused land subsidence in the Tokyo lowland. These artificial changes of natural conditions continue to affect natural disasters and countermeasures in the Tokyo lowland.
 Although large investments have been made since the 19^th century, Tokyo has suffered from a series of natural disasters because improvements to safety from natural disasters led to a concentration of property and people in Tokyo with increased potential for damage. Extensive damages due to flooding river, storm surges and earthquakes are now causing alarm. Serious warnings of the effects of urban development have been given due to vulnerable natural conditions. Irreversible changes to natural and social conditions in urban areas increase vulnerability, and may bring about a catastrophic disaster in the future.

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