【正文】 可以用安息角表示土壤承壓力，如，其中正、負號與前述意義相同。它們的對應(yīng)關(guān)系如表52所示。 橫臥板類型為適應(yīng)我國電氣化的發(fā)展，并根據(jù)我國的實際情況，廣泛地應(yīng)用鋼筋混凝土支柱。橫臥板的選擇如表53所示。Ⅰ型為60080080，孔距為310mm，孔徑為35mm；Ⅱ型為6001000100，孔距為410mm，孔徑為35mm。表53 橫臥板的選擇柱型路堤或路塹土壤安角(j)數(shù)量及型號上下H路堤地段(+)17176。2I1II30176。1II―33176。――38176。~22176。~32176。~37176。以上――H路堤地段(＋)17176。3I1II30176。~37176。以上――H路塹地段(－)17176。2I1Ⅱ30176。~37176。以上――H路堤地段(＋)17176。2I―30176。――33176。――38176。~22176。~32176。~37176。以上―― 接觸網(wǎng)接地我國交流電氣化鐵路接觸網(wǎng)的額定電壓為25kV。絕緣子雖起著絕緣作用，但是在通常情況下總有著微弱的泄漏電流經(jīng)絕緣體流向大地。當支柱對地有較大的接地電阻時，其電流就在支柱上形成過度電壓，嚴重時會危及人身安全。但是，由于支柱本身的電阻、基礎(chǔ)的電阻以及由基礎(chǔ)到鋼軌的過渡電阻等的阻值較大，在短路電流流過這些較大的電阻時，無疑就限制了短路電流的數(shù)值，致使因短路電流較小，不足以使繼電器的高速電流保護動作，而在短路點處形成時斷時續(xù)的電弧，這樣不僅不利于人身安全，而且會燒損電氣設(shè)備。 接觸網(wǎng)接地根據(jù)其作用不同分為工作接地和防護接地。站臺上金屬支柱使用雙接地也是出于防護的目的。為了達到上述目的，《鐵路電力牽引設(shè)計規(guī)范》規(guī)定：“接觸網(wǎng)金屬柱、金屬支持結(jié)構(gòu)和距接觸網(wǎng)帶電部分5m以內(nèi)的所有金屬結(jié)構(gòu)(信號機、水鶴、橋鐵欄柵等)均應(yīng)接地。由接地線(接地體)及接地部件組成的接地設(shè)備，稱為接地裝置。第6章 結(jié) 論本次畢業(yè)設(shè)計完成了大沙坪車站接觸網(wǎng)平面布置圖的設(shè)計，主要通過對線路資料的分析，一些基本的設(shè)計計算，與平面布置中設(shè)備的選擇，完成了此站場的平面布置圖與供電平面圖的CAD圖繪制。各個方面都要細心計算與校驗，要符合實際情況，比如跨距的選取與校驗部分，在選取了跨距后，一定要校驗，確定風偏移值滿足要求才行。本設(shè)計不足的地方有許多，比如在支柱布置時，由于對線路資料的分析不夠細致，導(dǎo)致了圖中與實際情況不符的后果，還有其他一些細節(jié)上的問題也不少。由于現(xiàn)場實際經(jīng)驗所限，在設(shè)計期間還走了許多彎路，但從中也吸取了一些寶貴的教訓(xùn)，為今后的工作積累了寶貴的經(jīng)驗財富，打下了一定的基礎(chǔ)。畢業(yè)設(shè)計是檢驗和鍛煉學(xué)生實際工程設(shè)計能力的一項教學(xué)環(huán)節(jié)。自課題的選擇到最終取得成果，張老師給予了我最細心的指導(dǎo)與不懈的支持。這是本次畢業(yè)設(shè)計能夠順利完成必不可少的因素。 (1)T: Tension of the overhead contact line [N], r : Weight per unit length of the overhead contact line [kg/m]Table 1 and Fig. 1 shows the pound catenary equipment deployed for JR East Shinkansen. The “Higher tension heavy pound catenary equipment” in Table 1 is the overhead contact line system that was improved when we increased the speed of the Tohoku Shinkansen to 275 km/h, and the “CS heavy pound catenary equipment” is the system that was improved in tests 15 years before where we successfully increased the speed to 425 km/h using the STAR21 test train on the Joetsu Shinkansen. In the high speed running tests this time, performance equivalent to that of the CS heavy pound catenary equipment was required. We were concerned, however, that development and construction could not be done in time, because the section that needed improvement was as long as approx. 60 km (60 drums) between Sendai and Kitakami.3. Issues in Improvement of the Overhead Contact Line System Issues in Current Collection Performance In running tests in 2003 using an operating train to get basic data for tests with FASTECH360, we measured remarkable strain (stress) on the contact wire over 1,000 μst at 360 km/h. We presumed the cause to be the pound effect of short intervals of 50 m for pantographs of the test train, singlearm contact strips and heavy pulloff arms. Also, we thought that another cause was that wave propagation was prevented because sufficient wave propagation velocity was not secured due to loose tension of the auxiliary messenger wire. Issues in Construction When we conducted improvement work of the CS heavy pound catenary equipment for the running tests of STAR21, for example, it took three days to improve one drum length (see Table 4). It was clear that if applying the same work method to the improvement this time, work would take more than half a year. Considering that and a balanced schedule with other maintenance work, we had to drastically shorten the work period.4. Development of Overhead Contact Lines with Good Current Collection Performance and Easy Improvability In improvements to enable a higher tension heavy pound catenary equipment to handle 360 km/h running, we set the following targets as requirements to improve the current collection performance and,at the same time, to allow effective work.1) Approx. 500 km/h1)* wave propagation velocity for the contactwire2) No change of the total tension of the overhead contact linesystem to avoid modification of support ponents3) Shortening the work period to 2/3 that of past work1Train speed ≤ wave propagation velocity multiplied by approx. or is desirable. In order to achieve 1), we made the diameter of the contact wire thinner (lighter in weight), from 170 mm2 to 110 mm2, and increased the tension from kN to kN. Regarding 2), to maintain kN total tension of the overhead contact line system, the total tension of the messenger wire and the auxiliary messenger wire needed to be decreased. As for the CS system, we decided to decrease the tension of the auxiliary messenger wire while keeping the tension of the messenger wire the same。 (SX) (2)S: Span length, T and r : As in Formula (1) Since the unit weight of the overhead contact line system is changed from kg to kg due to the introduction of 110 mm2 diameter contact wire, approx. kN tension of the messenger wire is desirable based on Formula (2).Table 2 shows the specs of the improved pound catenary equipment for the tests this time.5. Verification of Workability and Current Collection Performance of the Overhead Contact Lines Workability First, we verified the dropper length of the higher tension heavy pound catenary equipment (before improvement) and the improved pound catenary equipment. Table 3 indicates the parison results at the 50 m span length. The difference of the dropper length is within a few millimeters at other span lengths also. Therefore, replacement of droppers is not required. In this way, we could drastically simplify the improvement work pared to the CS heavy pound catenary equipment, as shown in Table. As shown in the above table, we could shorten the improvement work time of almost three days to two days. For the change of the tension of the messenger wire (replacement of anchor yokes), one of our partner panies developed a special jig to shorten the work time. The parison of before and after the improvement work using the data of an electric and track inspection car proved that the status before the improvement such as the height and devi