摘要
通过对渤海海峡跨海通道的地壳稳定性、海洋地质环境及海岛调查研究,证明渤海海峡适合修建跨海通道,且南桥北隧是最佳修建方案。修建跨海通道非常必要且具有非常高的经济效益。以公路通道计算,若能达到日均40 000辆的车流量,建成后每年将节减大约170亿元的燃油费及相应的燃油污染排放,7年即可收回投资成本,并可部分降低京津冀地区的雾霾水平和缓解交通压力。最佳修建线路是沿庙岛群岛轴部,这里地壳比周边更稳定、沉积物更薄,且实际跨海距离最短。蓬莱角至砣矶岛水深较浅,平均水深约20m,修桥是可行的;砣矶岛至大钦岛,平均水深35~40m;大钦岛至老铁山角,平均水深约50~55m。我们建议的南桥北隧方案,不同于前人提议的以北隍城岛作为桥隧连接地点的南桥北隧方案。砣矶岛面积7.05km^2,是首选的桥隧连接地点,大钦岛也可作为桥隧连接地点,可作为次选方案考虑。若砣矶岛作为桥隧连接地点,桥长约43km,隧道长约70km;若选大钦岛作为桥隧连接地点,则桥长约58km,隧道长约55km;桥隧总长约113km。南桥北隧方案,估计修建用时约为8~12年,总投资约为1 000~1 200亿元,工程使用年限以100年计。渤海是中国的内海,其风浪规模比东海、南海小。渤海海峡的南桥,受风浪的影响程度,虽比青岛胶州湾大桥大一些,但与杭州湾跨海大桥相仿,仅海水深度稍大一些。渤海海峡区估计每年约有60余天的风雾影响通行,这正好与两端邻近陆地上的风雾影响在时段和时间上相符合,可一起进行封闭或开通道路操作,实属正常,不应作为否定南桥北隧方案的理由。在海水较浅区域,修桥成本低,场地宽阔,容易施工且施工周期短。挖海底隧道成本较昂贵,施工难度大且周期长。基本上是隧道的长度决定了施工周期。全隧方案虽有"全天候"之美称,但由于全隧方案隧道长125km,投资2 500亿元,比我们提出的南桥北隧方案多花一倍以上的投资,修建用时也是多1倍以上,且必须在全部建完后才产生经济效益,故费钱费时、效率较低,是不适宜的。时代发展的趋势是,高速公路迅速崛起,铁路货运急剧下滑,公路通道比铁路通道更急需应优先考虑。南桥北隧方案,南桥是修建公路的南桥,北隧,有两种选择:如果通风等技术问题能够解决,应首先考虑修建公路通道的北隧;如果不能实现的话,那么,退而求其次修建铁路通道的北隧,用火车背负汽车过北隧,其效率低于公路通道汽车直接过北隧,运力不足也只能用滚装船轮渡汽车来补充。总之,不管是修公路通道还是铁路通道,甚至还是二者都要修,最佳方案都应该是南桥北隧,这样较省钱省时效率高,并在修建期间就可阶段性地产生经济效益。此外,南桥以地震基本烈度Ⅷ度设防,并能抗12级或以上台风及相应浪流,桥墩修建应尽量避开断裂带。北隧以地震基本烈度Ⅶ度设防。这正是:南部水浅利修桥,南桥北隧奇通道;阶段施工见效益,省钱省时效率高!
Surveys of earth crust stability, marine geo-environment and island geology along the Bohai Strait suggest that the Bohai Strait is feasible for cross-strait path construction, and the scheme of ＂bridge-south and tunnel-north＂ is the best and optimum one for construction among others. Construction of such a path way will certainly bring very high economic benefits to the region as well as to the country. A rough calculation for a highway with possible traffic flow of 40 000 vehicles per day suggests that 17 billion RMB of fuel charge could be saved every year with the facility, and it takes only six years to recover the investment cost in the years to come. It will certainly relieve the traffic pressure around the region and as the result reduce the haze caused by fuel emission. The optimum route for such a path is along the axis of the Miaodao islands because of more stable earth crust, thinner sediment cover, and shorter actual cross-sea distance there. From the Penglaijiao to the Tuoji Island the water depth is only 20m on average, while the water depth from Tuoji Island to Daqin Island is 35-40 m, and from the Daqin Island to the Laotieshanjiao 50- 55m on average. It is absolutely feasible for construction of a bridge system in the south. Our suggested scheme of ＂bridge-south and tunnel-north＂ is completely different from the alternative proposal which prefers to take the Beihuangcheng Island as the connection point for the bridge and the tunnel though they also agree to the idea of bridge-south and tunnel-north. We prefer to have the bridge - tunnel connection at the Tuoji Island, which is 7.05 km^2. The Daqin Island can be the second choice of the connection place for the bridge and the tunnel. If the Tuoji Island is selected as the bridge-tunnel connection, the bridge will be 58km long and the tunnel is 55km, with the total up to 113 km. Upon the above consideration, it is estimated that 8-12 years is needed to complete the construction with a total cost of 100-120 billion RMB if the service life of the system is assumed as 100 years. The Bohai Sea, as a continental sea of China, has weaker stormy waves comparing to the East China Sea and the South China Sea. The impact of stormy wave on the bridge across the Bohai Strait is supposed to be larger than that on the Jiaozhou Bay Bridge, but almost the same as the Hangzhou Bay Bridge, even the water depth of Bohai Strait is deeper. It is estimated that there would be more than 60 windy and foggy days every year when the traffic will be suspended in the Bohai Strait, almost the same as the period and time on the two land ends nearby. Therefore, it will not bring too much traffic problems to the region. Anyway, the weather should not be the reason to deny the scheme of ＂bridge-south and tunnel-north＂. The cost for bridge building is lower in the shallower water area, and the engineering will also proceed easily and complete in a shorter time in this broad zone. Moreover, tunneling costs more, needs more complicated engineering operation and of course much longer time. In fact, the length of tunnel is the factor which will decide the time required by the whole project. The scheme of ＂tunnel only＂ claims that it has the reputation of ＂performance under all the weather condition＂, but the ＂tunnel＂, which is 125 km long totally, will cost 250 billion RMB, at least twice over the scheme of ＂bridge-south and tunnel-north＇, and need twice or even more time for construction. And the economic benefits can only be generated after the whole project completed. So ＂tunnel only＂ scheme is costly,time-consuming and inefficient, and thus unrealistic for the time being. The developing trend of this area shows that the transport by highway rises rapidly, as the transport by railway declines sharply, so high- way has the priority over the railway as a more realistic consideration. In the proposed scheme of ＂bridge- south and tunnel-north＂, bridge-will be constructed only for highway, but the tunnels in the north, there might be two alternatives. If some of the technical problems, such as ventilation, can be solved, the tunnel in the north should take highway as the priority. If the problems cannot be solved, the option of railway has to be acceptable. The trains may bring vehicles through the tunnel,of course, it is less efficient than the highway tunnel which may bring vehicles running through directly. The reduced transport capacity can be compensated by ferry transportation. In conclusion, no matter which type of path is to be built, high- way or railway or both, the optimum scheme is the system with bridge-south and tunnel-north, which will be economic, time-saving and efficient, with economic benefits produced during different construction stages. The south bridge should be designed and constructed according to a basic seismic intensity of VIII and a typhoon attack of 12 degree and the associated stormy waves. The bridge pier should keep a distance as far as possible to faults and fault zones. The north tunnel should be designed according to the basic seismic intensity of VII. To sum up, the shallower water in the south is good for bridge construction, and the ＂bridge-south and tunnel-north＂ scheme will make a perfect cross-strait path; which will be really economic, time-saving and efficient,and benefits will be produced during each stages of construction.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2017年第3期1-16,共16页
Marine Geology & Quaternary Geology
基金
中国地质大调查项目(DD20160144
GZH201200504
GZH201200503)
国家重点研发计划(2016YFE0109600)
国家自然科学基金(40876033
40872167
41240022
41406082)
关键词
跨海通道
南桥北隧
海洋地质环境
修建方案
渤海海峡
cross-strait path
bridge-south and tunnel-north
marine geo-environment
scheme of construction
Bohai Strait
