Uplift of Sewage Manholes and Pipes During the 2004 Niigataken-Chuetsu Earthquake

About 1,400 sewage manholes were uplifted during the 2004 Niigataken-chuetsu earthquake in Japan. Many buried sewage pipes were also uplifted. Before the restoration work, detailed soil investigations were carried out to reveal the mechanism of the uplift. Based on the investigations, it was clarified that uplift occurred in mainly clayey grounds. No sand boils were observed on the clayey ground. However, boiled sands were observed just beside the uplifted manholes and above the buried pipes. During the construction of buried pipes and manholes, the ground was excavated first, the pipes and manholes were placed in the ditches, then the ditches were filled with sand. The soil investigation of the sand fill after the earthquake revealed that the sands were very loose and easy to liquefy. It was concluded that the uplift of the manholes and pipes occurred due to the liquefaction of the sand fill. In preparation for the restoration work, appropriate countermeasures for future earthquakes were discussed, and finally, the cement mixing method was selected.     

城镇排水系统设计与运行中的若干问题探讨

按照传统规范设计的排水系统,在实际运行中存在很多问题,不便于维护管理。为此对雨水系统设计运行中的以下内容提出了改进措施:雨水口和淹没出水口的设置,在适当位置铺设雨水系统的连通管,积水严重段临时增设直通污水检查井的雨水口,合理铺设住宅区雨水系统、加快雨洪资源利用的推广应用等。另外,还对污水系统中的以下内容提出了改进措施:设计运行改进检查井构造,在适当位置铺设污水管系统之间的连通管,铺设污水厂进水总管复线,闸槽井做法,旧泵站集水池有效容积和最低水位线的确定,污水厂的规模和效率,排水体制的确定等,可供相关人员参考。     

Liquefaction in Tohoku district during the 2011 off the Pacific Coast of Tohoku Earthquake

Information on the liquefaction and the liquefaction-induced damage in the Tohoku district during the 2011 off the Pacific Coast of Tohoku Earthquake has been compiled. The liquefaction in this report was mainly identified by sand boils. It caused damage to earth structures and residential houses, as well as the uplift of manholes. A comparison of geological maps and aerial photos, before and after the earthquake, shows that many of the liquefied sites were old river beds and developed areas. Liquefaction in the tsunami-affected areas was difficult to identify as the evidence of liquefaction had been washed away by the tsunami. However, the liquefaction was identified through interviews with residents and by photos and videos taken before the arrival of the tsunami. Liquefaction was also observed at Sendai Airport, but the runaway was not damaged because it had been remediated against soil liquefaction.     

城市排水设施中恶臭源的产生及其治理对策的研究

城市排水设施中恶臭的产生有其必然性和极大的危害性,恶臭源的分布也具有一定的规律性。城市排水设施中产生的恶臭污染物主要是硫化氢气体。目前可以从恶臭源的抑制和收集处理两方面制定恶臭防治对策,采取向排水管道或窨井中加药或充氧等,抑制恶臭的产生;在污水处理厂或排水泵站中采用恶臭源封闭并用吸附法、氧化法和生物法集中除臭处理,均可获得较好的效果。     

Experimental estimation of the head loss coefficient at surcharged four-way junction manholes

ABSTRACT

The head loss caused by the surcharged flow from four-way junction manholes is the main cause of increased flood damage in urban areas. The flow pattern significantly varies depending on the inflow conditions of the inlet pipes and constitutes the flow conditions of a four-way junction manhole, three-way junction manholes, and middle manholes. Therefore, the head loss changes with various manhole shapes must be analyzed. In this study, physical model study apparatus was prepared. Various flow rate conditions were selected by changing the flow rate ratios of the inlet pipes at 10% intervals. The head loss coefficients were also estimated. A head loss coefficient range diagram was generated based on the results. A head loss coefficient empirical formula that considers all flow conditions for surcharged four-way junction manholes is proposed. The proposed equation should be applicable to the design and assessment of drainage systems with varying inlet pipe flow rates.     

Environmental effects on concrete using Ordinary and Pozzolana Portland cement

Wastewater treatment plant consists of pipe lines and lift stations. These plants consist of concrete pipes, manholes, pump stations, interceptors and wet wells. Entire wastewater (WW) system is forced to chemical attack due to the presence of sulphate and acid available in WW. It leads to the damage in the interior wall or structure of a sewer pipe and lift station. A concrete structure when exposed to different environments, the life of the structure is drastically reduced. Main cause of the deterioration is corrosion or erosion. The defective structures are replaced periodically which leads to indirect loss in the national growth. In other words, the failure of these structures may lead to invest more on the repair and rehabilitation.In this study, the strength of the concrete in various environments has been investigated using different techniques such as compressive strength, flexural test, rapid chloride permeability, weight loss measurements, linear polarization and open circuit potential. Microbiological examinations were also analyzed. Two types of cement namely Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC) with one mix ratio were used for complete study. Concrete specimens exposed in three environments namely: normal water (NW Potable water), domestic sewage water (DSW) and textile wastewater (TWW). From the results, it is observed that PPC exposed in different media shows better performance than OPC in both mechanical and electrochemical studies.     

Lessons for countermeasures using earth structures against tsunami obtained in the 2011 Off the Pacific Coast of Tohoku Earthquake

Since many infrastructures, such as sea walls, sand beaches, forests, etc., were severely damaged or destroyed by the tsunami that occurred due to the 2011 Off the Pacific Coast of Tohoku Earthquake, it is said that the resistant functions of the above structures against tsunami attacks did not perform well. However, some structures are known to have resisted the tsunami, based on field surveys conducted after the earthquake by the authors and others; and thus, the resistant functions of those infrastructures against tsunami should be estimated more properly. This paper focuses on earth structures, including river levees and road embankments, both damaged and undamaged, at 13 sites in Miyagi Prefecture, Chiba Prefecture, and Ibaraki Prefecture. They have been investigated through field surveys and other related data, such as satellite photographs taken before and/or after the tsunami. Furthermore, 10 dug pools, eroded by the flood stream on the back side of sea walls and banks during the tsunami, are also investigated to clarify their effects against tsunami attacks for use as future hardware countermeasures. Based on the above field investigations, several important lessons on hardware countermeasures against tsunami, using earth structures, are discussed. And, performance-based design concepts for reconstruction after this earthquake and for the reduction of future tsunami damage are discussed and proposed.     

Effect of earthquake ground motions on soil liquefaction

During the 2011 off the Pacific Coast of Tohoku Earthquake, which was the largest earthquake in Japanese history, the soil liquefaction phenomenon was observed over a wide area along the Pacific Coast in Tohoku and in Kanto, including the Tokyo Bay area. Extensive damage was caused by the effect of soil liquefaction to residential lands and houses, as well as to infrastructures, such as roads, rivers, ports, and water supply/sewage systems. Since the 2011 off the Pacific Coast of Tohoku Earthquake occurred in a mega-size fault zone, with an area of 500 km×200 km, the duration of the strong shaking was extremely long compared to that in the data recorded for past earthquakes. Clarifying the effect of the characteristics of the ground motion on the soil liquefaction mechanism is one of the essential studies to be conducted, and effective countermeasures for the damaged structures need to be found.This paper presents the strong motion observation data obtained on the liquefied and the non-liquefied grounds and raises preliminary discussions on the mechanism of soil liquefaction based on this data. The effect of the duration and the number of cyclic loadings on the progress of the soil liquefaction phenomenon is also compared with that found in past strong motion data.     

污水泵站设备运行管理经验

对济宁市4座污水中途提升泵站基本运行情况作了简要介绍,通过分析近年来各个泵站日均提水量,指出必须新建污水处理厂,具体阐述了污水泵站设备运行管理经验,提出应不断完善管理制度,对泵站设备进行更新改造,开发完善泵站自动控制系统。     

水工构筑物质量问题的产生原因及预防措施

针对自来水厂、污水处理厂、雨(污)水泵站中,各种水池、泵房、井室等水工构筑物经常发生的整体失稳、渗漏等质量问题所产生原因进行了详细分析,并从监理工程师的角度提出了施工过程中应采取的预防措施,对于提高工程质量提供了很好的借鉴.     

多个一体化预制泵站并联用于污水提升工程实践

在天津天狮大学校外配套污水泵站及管网工程设计中,针对三个收水范围末端污水管线高程无法衔接、泵站建设区域有限、污水量变化较大等情况,通过方案比选后采用了多个一体化预制泵站并联的形式提升污水至污水厂。泵站控制设计中,在泵站出水端及交汇节点处设置了压力传感器,实现了多个变频潜污泵协同调节控制,从而克服了压力污水管网中压力不平衡问题,顺利实现了同时排出多个区域污水的目的。     

Process Automation of The Hague Sewage-Treatment Plant

The process control of sewage-treatment plants is normally carried out by conventional means. Special circumstances forced the application of a state-of-the-art process automation system for The Netherlands'largest sewage-treatment plant (Houtrust) at The Hague.
The plant incorporates the use of oxygen-enriched air for use in the secondary treatment process, and the final settling tanks are constructed one above the other (in two tiers). The automation system is built up with locally-placed process computers, and a central video operating system is included with a data-processing computer; these are interconnected by a data transmission bus of redundant design. The central control system is also connected to the main sewage pumping stations of The Hague district, for collecting data and controlling these stations from the plant.
After the start-up of the plant, it took several months of tuning the control system to gain proper process control, the main problem being the influence of pump switching in the intermediate pumping stations on the oxygen supply to the aeration tanks.     

Characteristics of liquefaction in Tokyo Bay area by the 2011 Great East Japan Earthquake

The 2011 Great East Japan Earthquake caused the severe liquefaction of reclaimed lands in the Tokyo Bay area, from Shinkiba in Tokyo through Urayasu, Ichikawa and Narashino Cities to Chiba City. However, the reclaimed lands that had been improved by the sand compaction pile method, the gravel drain method or other methods did not liquefy. The reclaimed lands that did liquefy had been constructed after around 1966 with soil dredged from the bottom of the bay. The dredged and filled soils were estimated to have been liquefied by the earthquake. Seismic intensities in the liquefied zones were not high, although the liquefied grounds were covered with boiled sand. Most likely it was the very long duration of the main shock, along with the large aftershock that hit 29 min later, which induced the severe liquefaction. Sidewalks and alleys buckled at several sites, probably due to a kind of sloshing around of the liquefied ground. Moreover, much sand boiled from the ground and the ground subsided significantly because the liquefied soil was very fine. Many houses settled notably and tilted. In Urayasu City, 3680 houses were more than partially destroyed. Sewage pipes meandered or were broken, their joints were extruded from the ground, and many manholes were horizontally sheared. This remarkable damage may also have occurred due to the sloshing around of the liquefied ground.     

Field investigation and model tests on differential settlement of houses due to liquefaction in the Niigata-ken Chuetsu-Oki earthquake of 2007

A massive earthquake struck the Niigata Chuetsu-Oki region of Japan on July 16th, 2007, claiming 11 lives and damaging about 6000 houses. The earthquake had a magnitude of 6.8, with data from an accelerograph managed by a nationwide strong-motion observation network known as Kyoshin Net (K-net) showing a maximum value of 668 gal (NS). In the Matsunami district of Kashiwazaki city (located on land filled and developed as a residential area from around 1970 onward) about 3 km northeast of Kashiwazaki Railway Station, many houses were damaged due to liquefaction. A field investigation, including a boring survey, surface wave exploration and measurement of differential settlement of houses knocked aslant by soil liquefaction, was conducted to determine the relationship between the extent of damage to houses and the area׳s geological structure. It was found that most houses severely damaged due to liquefaction were located around the boundary between sand dunes and the local river delta. Additionally, the relationships linking sloping geological structure, the thickness of the liquefaction layer and total/differential settlement of houses were clarified from the results of shaking table model tests conducted in this study. Test results showed that it is important to consider multidimensional influences caused by sloping geological structure in the estimation method of liquefaction potential in order to predict and assess degree of damage to houses due to liquefaction.     

2011年日本东北地区太平洋近海地震地基液化灾害综述

2011年3月11日,日本太平洋东海岸发生M_w 9.0级大地震,并引发巨大海啸,导致了日本东北和关东地区大面积的地基液化震害。通过现场震害调查和最新资料分析,首先较为系统地介绍了日本地震受灾区的液化宏观现象和典型震害特征。其次,研究了余震再液化和地震-海啸耦合灾害的破坏机制和特征,指出余震再液化受地震力大小、应力历史及超孔隙水压力消散程度的影响,并将地震和海啸耦合破坏过程分为3个阶段：震后液化阶段、间歇期恢复阶段、海啸流滑破坏阶段;最后,对此次强震中有关抗液化地基处理方法的有效性进行了分析与探讨,以期为今后的地基抗液化设计提供参考与借鉴。     

浅析全地埋式污水提升泵站的优势及其应用

通过比较全地埋式污水提升泵站与传统污水提升泵站的优缺点,介绍全地埋式污水泵站的优势及应用前景,并对粉碎型格栅除污机等关键设备的选用和地埋泵站的应用注意事项提出建议。     

Building damage associated with geotechnical problems in the 2011 Tohoku Pacific Earthquake

An overview of the geotechnical aspects of the building damage due to the 2011 Tohoku Pacific Earthquake is presented, based on field reconnaissance made after the earthquake. It is shown that (1) Extensive soil liquefaction occurred along the coast of Tokyo Bay and around the floodplain of the Tonegawa River. Liquefaction was primarily found within the relatively newly reclaimed area, with numerous sand boils and large ground settlements up to 60 cm, accompanied by the settlement/tilting of wooden and reinforced concrete buildings supported by spread foundations. The extent and the distribution of the damage were significantly affected by the local soil conditions, including the thickness and the age of the reclaimed fills, the depth to the bedrock or the natural site period, and whether remedial measures had been taken against soil liquefaction, as well as the effects of structure–soil–structure interaction. (2) Numerous houses in Sendai's hilly residential areas constructed with the cut-and fill method were badly damaged not only by the simple collapse of retaining walls, but also by slope failures in the fills. It was found that most of the slope failures occurred on earth fills. (3) Several pile-supported buildings tilted and settled not only in the Tohoku region, but also on the Kanto plain, implying damage to pile foundations. Ground subsidence with sand boils around those buildings suggests that soil liquefaction might have played a significant role in intensifying the damage. (4) Within Onagawa and Rikuzen-Takata, several steel and reinforced concrete structures were knocked over by tsunami surges, probably after having suffered damage to their pile foundations. Much of the pile damage was concentrated (a) at the joints between pile caps and the piles themselves and (b) near the pile heads. The buildings suffering such damage were old; apparently their pile foundations were not designed to withstand earthquakes.     

粉碎型格栅用于污水泵站存在的问题和使用建议

粉碎型格栅具有环境友好、可实现无人值守及泵站地埋化等优点,但也存在投资费用高、维修周期长、维修费用贵、运行能耗高、对污水处理厂影响大等问题,基于杭州市污水泵站应用粉碎型格栅的经验,提出了设计和运行管理方面的相关建议。     

太原市城市污水现状调查及结果分析

以汾河沿岸的13条排污渠、9座污水泵站和2座污水处理厂为主要调查对象,对太原市目前的排水状况和城市污水排放量进行了调查,并对调查结果和调查中发现的问题进行了探讨分析,并提出了具体的建议,从而解决太原市城市污水处理问题。     

浙江省城市污水处理厂产泥现状与处置对策

目前浙江省污水处理厂的污泥产量为100×104t/a,污泥处置问题日益突出。笔者通过调查和统计,分析了浙江省污水处理厂污泥的产生情况、特点和处置状况,并对未来的污泥处置提出了对策和建议。